Learn Hardcore German: Ich will jetzt zurückgehen.

In German will is the first‑person singular of the verb wollen (to want). So Ich will jetzt zurückgehen translates as “I want to go back now,” not “I will go back now.” German often uses the simple present for near future. If you want to form a future tense, you use werden:
• Ich werde jetzt zurückgehen. (“I will go back now.”)

Why is zurückgehen written as one word here, and why doesn’t it split into zurück and gehen?

Zurückgehen is a separable‑prefix verb. When the verb appears as an infinitive—especially after a modal verb like will—the prefix stays attached. Separable verbs only split when the finite verb is in second position in a main clause, for example:
• Ich gehe jetzt zurück.
After a modal, the entire infinitive (zurückgehen) sits at the end of the clause.

Where does the adverb jetzt belong? Can I move it?

German adverbs of time are flexible but typically follow the finite verb in V2 clauses.
• Neutral word order: Ich will jetzt zurückgehen.
You can also front jetzt for emphasis:
• Jetzt will ich zurückgehen.
Putting it at the very end (Ich will zurückgehen jetzt) is grammatically possible but sounds marked in spoken and written German.

Does zurückgehen need a direct object or a preposition to indicate where I’m going back to?