Ich fahre morgen mit dem Zug nach Wien.

In a normal German main clause, the finite verb usually goes in position 2.

So in Ich fahre morgen mit dem Zug nach Wien:

• Ich = position 1
• fahre = position 2

Everything else comes after that.

This is one of the most important German word order rules. Even if you start with another element, the verb still stays second:

• Morgen fahre ich mit dem Zug nach Wien.

Here, morgen is in position 1, so fahre still has to stay in position 2, and ich moves after it.

Because fahren is the infinitive form, and German verbs have to be conjugated to match the subject.

For fahren in the present tense:

• ich fahre
• du fährst
• er/sie/es fährt
• wir fahren
• ihr fahrt
• sie/Sie fahren

So with ich, the correct form is fahre.

No. Fahren is broader than English drive.

It is commonly used for traveling by some kind of vehicle or transport, for example:

• mit dem Zug fahren = travel/go by train
• mit dem Auto fahren = drive/go by car
• mit dem Bus fahren = go by bus
• Rad fahren = ride a bike

So in this sentence, fahre means something like am traveling / am going, not necessarily that the speaker is personally operating the train.

It can be at the beginning, but it does not have to be.

German is more flexible than English about what comes first. Both are natural:

• Ich fahre morgen mit dem Zug nach Wien.
• Morgen fahre ich mit dem Zug nach Wien.

The difference is mostly one of focus or style:

• starting with Ich puts the speaker first
• starting with morgen emphasizes the time

Both are correct.

Because mit always takes the dative case.

The noun der Zug becomes dem Zug in the dative singular:

• nominative: der Zug
• dative: dem Zug

So:

• mit dem Zug = by train

This is a very common pattern:

• mit dem Auto
• mit dem Bus
• mit der U-Bahn

Most city names in German are used without an article, just like in English.

So you say:

• nach Wien
• in Wien
• aus Wien

not normally nach dem Wien or in dem Wien.

A few place names do take articles, but most cities do not. For a beginner, it is safe to think: city names usually appear without der/die/das.

German uses different prepositions for different kinds of destination.

With cities and countries without an article, German usually uses nach to mean to:

• nach Wien
• nach Berlin
• nach Deutschland

In Wien means in Vienna, not to Vienna.

Zu is used for different kinds of destinations, often people or places seen as destinations in a more general sense:

• zu meiner Freundin
• zum Arzt
• zur Schule

So for a city like Vienna, nach Wien is the normal choice.

Because all nouns are capitalized in German.

So in this sentence:

• Ich is capitalized because it starts the sentence
• Zug is capitalized because it is a noun
• Wien is capitalized because it is a proper noun

This is a major difference from English and a very useful clue when reading German.

Grammatically, it is present tense:

• Ich fahre = I travel / I am traveling / I go

But German very often uses the present tense to talk about the future when the time is clear. Here, morgen makes the future meaning obvious.

So:

• Ich fahre morgen ... = I’m going tomorrow ...

German could also use werden for the future, but it is often unnecessary:

• Ich werde morgen mit dem Zug nach Wien fahren.

That is correct too, but the simple present is very common and natural.

A very common German pattern is:

time - manner - place

In this sentence:

• morgen = time
• mit dem Zug = manner/means
• nach Wien = place/destination

So:

• Ich fahre morgen mit dem Zug nach Wien.

This order is very typical and sounds natural. German word order is flexible, but this pattern is a helpful guideline.

You probably could be understood, but it sounds much less natural in a neutral context.

German does allow some flexibility, but not every possible order sounds equally good. The most natural neutral version is:

• Ich fahre morgen mit dem Zug nach Wien.

Other natural alternatives include:

• Morgen fahre ich mit dem Zug nach Wien.
• Mit dem Zug fahre ich morgen nach Wien.
  (This emphasizes mit dem Zug.)

So yes, German word order is flexible, but it is best to learn the most common patterns first.

After nach, a destination noun is normally treated as being in the dative, but with a city name like Wien, you do not see any article ending, so nothing changes visibly.

That is why learners often just memorize the chunk:

• nach Wien
• nach Berlin
• nach Hamburg

The important practical point is: for movement to a city, use nach + city name.

Yes, but context matters.

• morgen with a small m usually means tomorrow
• morgens means in the mornings
• am Morgen means in the morning

In your sentence, Ich fahre morgen ..., it clearly means tomorrow.

Be careful with capitalization:

• morgen = tomorrow
• der Morgen = the morning

So capitalization can change the meaning.