jīntiān shì wǒ de shēngrì, wǒ zhǐ xiǎng gēn jiārén zài jiā ānjìng de chī wǎnfàn.

Time words like 今天, 明天, 昨天 usually go at the beginning of the sentence to set the time frame:

• 今天是我的生日。 – Today is my birthday.
• 明天我要上班。 – Tomorrow I have to work.

我是今天生日 is not natural. For birthday, Chinese normally uses a “subject + 是 + noun phrase” pattern:

• 今天是我的生日。 – Today is my birthday.
• 明天是他的新工作第一天。 – Tomorrow is his first day at the new job.

So: put 今天 at the start, and keep 是 right before 我的生日.

Yes, here 是 works very similarly to English “to be” in the “A is B” pattern:

• 今天是我的生日。 – Today is my birthday.

But note:

• Chinese does not use 是 for linking a subject with an adjective:
  • 我很累。 (not 我是累) – I am tired.
  • 天气很好。 (not 天气是很好 in normal statements) – The weather is very good.

Use 是 to link:

• nouns to nouns (他是老师 – He is a teacher),
• pronouns to nouns (那是我的书 – That is my book),
• or in focus/emphasis structures (是……的 pattern).

的 is a possessive marker, similar to English ’s or “of”:

• 我
  • 的
    • 生日 → 我的生日 – my birthday
• 他
  • 的
    • 家人 → 他的家人 – his family
• 中国
  • 的
    • 文化 → 中国的文化 – Chinese culture

Structure:
[owner] + 的 + [thing owned]

In spoken Chinese, 的 is sometimes dropped with very close relationships or set phrases (e.g. 我妈, 我家), but 我的生日 is completely standard and natural.

只 (zhǐ) means “only / just”, limiting the action that follows:

• 我想跟家人在家安静地吃晚饭。
  – I want to eat dinner quietly at home with my family. (neutral)
• 我只想跟家人在家安静地吃晚饭。
  – I only want to eat dinner quietly at home with my family. (and nothing more)

So 只 emphasizes that this is the only thing you want, often implying:

• you don’t want a party,
• you don’t want to go out,
• you don’t want other activities.

In this sentence, 想 means “want to / would like to”, but it sounds softer and more polite than 要.

• 我想跟家人吃晚饭。 – I would like to eat dinner with my family. (polite, wish/desire)
• 我要跟家人吃晚饭。 – I want to / I’m going to eat dinner with my family. (stronger, more definite)

General ideas:

• 想: desire, intention, wish; softer.
• 要: stronger intention, plan, or necessity.

Also remember: 想 can mean “to think / to miss” in other contexts:

• 我想你。 – I miss you.
• 我想，这样更好。 – I think this is better.

Here it’s clearly “want to” because it’s followed by an action (跟家人在家安静地吃晚饭).

In this sentence:

• 跟家人 = with (my) family

跟 and 和 overlap a lot in meaning, and both can often mean “with / and”:

• 跟家人吃晚饭
• 和家人吃晚饭

Both are acceptable and understood as “eat dinner with family”.

Typical tendencies:

• 跟 is especially common for “with (someone)” in the sense of doing something together:
  
  • 跟朋友去看电影 – go watch a movie with friends
• 和 very commonly means “and” when listing items:
  
  • 苹果和香蕉 – apples and bananas

In casual speech, 跟 is extremely frequent for “with”. Your sentence with 跟家人 sounds completely natural.

家人 and 家 are different:

• 家人 = family members / relatives in the household (people)
• 家 = home / house / family (place or abstract “family”)

In your sentence:

• 跟家人 – with my family (people you eat with)
• 在家 – at home (location where you eat)

So:

• 跟家人 – “with family members”
• 跟家 – sounds wrong here; 家 alone doesn’t mean “with my family” in this structure.

You could say:

• 我想跟家人在家吃晚饭。 – I want to eat dinner at home with my family.

But 跟家在家 is incorrect because 家 there is a place, not a person.

在 + place is a common way to mark location of an action:

• 在家 – at home
• 在学校 – at school
• 在公司 – at the office

Basic structure here:

• 我只想跟家人在家安静地吃晚饭。
  – I only want to (with family) (at home) (quietly) eat dinner.

In Chinese, location and manner normally come before the main verb:

• 我在家吃饭。 – I eat at home.
• 我在图书馆认真地学习。 – I study carefully in the library.

So 在家 naturally comes before 吃 to say where the eating happens.

• 安静 = quiet, peaceful
• 安静地 = quietly / in a quiet way

地 (de) here is an adverb marker. It turns an adjective or descriptive phrase into something that modifies the verb, like “-ly” in English:

• 慢 → 慢地走 – walk slowly
• 认真 → 认真地学习 – study seriously
• 安静 → 安静地吃晚饭 – eat dinner quietly

So in your sentence:

• 安静地吃晚饭 = eat dinner in a quiet way.

Without 地, 安静吃晚饭 is still understandable in speech, but it sounds more informal or a bit abrupt. 安静地吃晚饭 is the standard, grammatically clear form.

地 (de) and 的 (de) are different particles with different uses:

1. 的 – describes or shows possession, used before nouns:

   • 我的生日 – my birthday
   • 安静的房间 – a quiet room
   • 漂亮的衣服 – pretty clothes

2. 地 – marks adverbs, used before verbs:

   • 安静地吃晚饭 – eat dinner quietly
   • 认真地工作 – work seriously
   • 高兴地说 – say (something) happily

Quick rule of thumb:

• 的
  • noun
• 地
  • verb

In your sentence:

• 我的生日 → 的 before 生日 (noun)
• 安静地吃晚饭 → 地 before 吃 (verb)

• 吃饭 = eat (a meal), often generic
• 吃晚饭 = eat dinner / have supper (specifically evening meal)

So:

• 我刚吃饭。 – I just ate (a meal).
• 我刚吃晚饭。 – I just ate dinner.

晚饭 and 晚餐 both mean dinner:

• 晚饭 – more colloquial, everyday speech
• 晚餐 – slightly more formal or written, can sound a bit more elegant

Your sentence with 吃晚饭 is perfectly natural, conversational Mandarin.

The original has:

• 今天是我的生日， 我只想跟家人在家安静地吃晚饭。

This is actually two clauses:

1. 今天是我的生日。 – Today is my birthday.
2. 我只想跟家人在家安静地吃晚饭。 – I only want to eat dinner quietly at home with my family.

They are closely related, so writing them with a comma is very natural in Chinese, similar to “Today is my birthday, and I only want to …” in English.

You can split them:

• 今天是我的生日。 我只想跟家人在家安静地吃晚饭。

Both ways are correct. The comma version feels a bit more fluid as one thought.

Yes, there is third-tone sandhi:

• 我 (wǒ) – 3rd tone
• 只 (zhǐ) – 3rd tone
• 想 (xiǎng) – 3rd tone

In natural speech:

• 我只想 is pronounced like:
  wó zhǐ xiǎng → often heard as (2nd) + (3rd) + (3rd)

Pattern:

• When two 3rd tones are together, the first one becomes 2nd tone in pronunciation:
  • 我只 → wó zhǐ (2–3)
  • Then 只想 also interacts, but learners mainly need to know it won’t be three very “deep” 3rd tones in a row.

You don’t change the written tones, but the spoken melody will shift to make it smoother.