من به دوستم نوشتم که فردا بعد از کلاس به کتابخانه میروم.

Yes. In Persian, subject pronouns are often dropped because the verb ending already shows the person.

• نوشتم = I wrote
• می‌روم = I go / I am going

So من is not strictly necessary here. The sentence could also be:

به دوستم نوشتم که فردا بعد از کلاس به کتابخانه می‌روم.

Including من can add a little emphasis or clarity, especially for learners or in more careful writing.

به is a very common preposition, and here it has two different but related uses:

• به دوستم = to my friend
• به کتابخانه = to the library

So in this sentence, the first به marks the person you wrote to, and the second marks the place you are going to.

دوستم means my friend.

It is made of:

• دوست = friend
• ـم = my

So:

• دوستم = my friend
• دوستت = your friend
• دوستش = his/her friend

This ـم is a possessive ending attached directly to the noun.

نوشتم is the simple past: I wrote.

It is formed from the past stem of نوشتن (to write) plus the ending for I:

• نوشت
  • م = نوشتم

By contrast:

• می‌نوشتم usually means I was writing or I used to write

So نوشتم is the normal form for a completed action in the past: I wrote.

که introduces the content of what was written. Here it works like that in English:

• I wrote to my friend that...

So the sentence breaks into two parts:

• من به دوستم نوشتم
• که فردا بعد از کلاس به کتابخانه می‌روم

In spoken Persian, که is extremely common for linking clauses like this.

Because the second clause refers to a future plan: tomorrow after class I’m going to the library.

In Persian, the simple present often expresses a future action, especially when there is a time word like فردا (tomorrow).

So:

• فردا می‌روم = I will go tomorrow / I’m going tomorrow

This is very natural Persian. You do not need a special future form here.

Yes, Persian does have a future tense, for example:

• خواهم رفت = I will go

So you could say:

من به دوستم نوشتم که فردا بعد از کلاس به کتابخانه خواهم رفت.

But in everyday Persian, the simple present می‌روم is much more common for planned future actions. In this sentence, می‌روم sounds more natural.

بعد از کلاس means after class.

It is made of:

• بعد = after
• از = from/of
• کلاس = class

Together, بعد از functions as a fixed expression meaning after.

So:

• بعد از کلاس = after class
• بعد از کار = after work
• بعد از ظهر = afternoon

Persian does not have a word exactly like English the.

So کتابخانه can mean:

• the library
• a library

The context tells you which one is meant. In this sentence, English often translates it as the library, because that sounds natural in context, but Persian itself does not mark definiteness the way English does.

Persian usually follows Subject – Object/Complements – Verb.

So the main clause is:

• من
• به دوستم
• نوشتم

Literally: I to my friend wrote

And the subordinate clause is:

• فردا
• بعد از کلاس
• به کتابخانه
• می‌روم

Literally: tomorrow after class to the library I-go

The verb usually comes at the end of the clause, which is one of the most important word-order patterns in Persian.

Yes, it is normal.

Persian commonly uses نوشتن به کسی to mean to write to someone:

• به او نوشتم = I wrote to him/her
• به دوستم نوشتم = I wrote to my friend

The actual thing written, such as a letter or a message, can be left unstated if it is obvious from context.

The standard modern spelling is می‌روم with a نیم‌فاصله (half-space / zero-width non-joiner).

You may also see میروم, especially in less careful typing, but می‌روم is preferred.

It is pronounced roughly like mi-ram in standard spoken Persian.

A few helpful notes:

• Written formal Persian: می‌روم
• Colloquial spoken Persian: often می‌رم / میرم
• Meaning here: I’m going / I will go

Sometimes, especially in casual speech, Persian can omit که if the meaning is still clear. But in a sentence like this, keeping که is very natural and often clearer.

So:

• من به دوستم نوشتم که... = very normal
• Omitting که is possible in some contexts, but learners should usually keep it until they get more comfortable with Persian clause structure.