Ich schreibe meinen Vornamen.

Because German verbs change form to match the subject.

The basic form is schreiben, but with ich in the present tense, the correct form is schreibe.

• ich schreibe
• du schreibst
• er/sie/es schreibt

So Ich schreibe ... means the verb is correctly conjugated for I.

Because mein changes its ending depending on the gender, number, and case of the noun that follows it.

Here, Vorname is:

• masculine
• singular
• in the accusative case

So mein becomes meinen.

A useful comparison:

• mein Vorname = my first name, as the subject
• meinen Vornamen = my first name, as the direct object

Because Vorname is a weak masculine noun.

That means it adds -n in some cases, including the accusative singular.

Its forms are:

• der Vorname = nominative
• den Vornamen = accusative
• dem Vornamen = dative

So in this sentence, Vornamen is correct because it is the direct object of the verb.

Because it is the direct object of schreibe.

Ask yourself: What am I writing?

Answer: meinen Vornamen

In German, the thing directly affected by the action is usually in the accusative. So after schreiben, the thing being written is commonly accusative.

Because meinen already does the job that an article would normally do.

In German, a possessive word like mein, dein, sein, and so on usually takes the article position.

So you say:

• meinen Vornamen
• den Vornamen

but not normally both together in a simple sentence.

Vorname specifically means first name or given name.

Name is more general and can mean name in a broad sense.

Related words:

• Vorname = first name
• Nachname = last name / surname
• Familienname = family name / surname
• Name = name

So this sentence is more specific than just saying Ich schreibe meinen Namen.

Because all nouns are capitalized in German.

So words like these are capitalized:

• Ich only because it begins the sentence
• Vornamen because it is a noun

If ich appeared in the middle of a sentence, it would normally be lowercase:

• Dann schreibe ich meinen Vornamen.

Unlike English, German does not capitalize ich just because it means I.

Yes, but the normal order here is the most neutral one.

The standard main-clause pattern is:

• subject + verb + other elements

So:

• Ich schreibe meinen Vornamen.

You can move another element to the front for emphasis:

• Meinen Vornamen schreibe ich.

But in a normal main clause, the conjugated verb still stays in second position.

Yes. Schreiben often takes a direct object in the accusative when you say what you are writing.

Examples:

• Ich schreibe einen Brief.
• Ich schreibe meinen Namen.
• Ich schreibe das Wort.

So in Ich schreibe meinen Vornamen, the object tells us what is being written.

A rough pronunciation guide is:

• Ich: the ch is a soft sound that does not exist exactly in English
• schreibe: the ei sounds like English eye
• meinen: the ei again sounds like eye
• Vornamen: roughly FOR-nah-men

A very rough English-style approximation would be:

ikh SHRY-buh MY-nen FOR-nah-men

But the real German sounds are a bit different, especially the ch in ich.