Learn Hardcore Indonesian: Biografi itu harus ditulis rapi, lalu kami belajar mengedit teks bersama. - That biography must be written neatly, then we learn to edit the text together.

Itu literally means that or the. Here, biografi itu is best understood as that biography / the biography (something already known in the context).

Without itu:

Biografi harus ditulis rapi = A biography / biographies must be written neatly (more general).

With itu:

Biografi itu harus ditulis rapi = That specific biography must be written neatly (refers to a particular biography already identified).

Why is it harus ditulis and not harus menulis?

Harus ditulis is passive; harus menulis is active.

Biografi itu harus ditulis rapi
= The biography must be written neatly. (focus on the biography, the result)
Kami harus menulis biografi itu dengan rapi
= We must write that biography neatly. (focus on us as writers)

Indonesian often uses the passive form when:

The object (here, biografi itu) is the topic.
The agent (the person who writes) is obvious from context or not important.

So the sentence emphasizes the biography and its condition, not who writes it.

Why is it ditulis rapi and not ditulis dengan rapi?

In Indonesian, adjectives can often function like adverbs directly, without dengan.

rapi = neat / tidy
dengan rapi = neatly (literally with neatness)

Both are correct:

Biografi itu harus ditulis rapi.
Biografi itu harus ditulis dengan rapi.

The version without dengan is shorter and very natural in speech and writing. Adding dengan can sound slightly more formal or emphatic, but meaning is the same here.

What exactly does lalu mean here, and could we use kemudian or setelah itu instead?

Lalu means then / and then / after that and links two actions in sequence.

Biografi itu harus ditulis rapi, lalu kami belajar mengedit teks bersama.
= First the biography has to be written neatly, then we learn to edit text together.

You can usually replace lalu with:

kemudian (a bit more formal, similar meaning)
setelah itu (after that, slightly more explicit about sequence)

Examples:

…, kemudian kami belajar mengedit teks bersama.
…, setelah itu kami belajar mengedit teks bersama.

All are acceptable; lalu is common and neutral.

Is the comma before lalu necessary?

The comma is optional but common and helpful.

Biografi itu harus ditulis rapi, lalu kami belajar mengedit teks bersama.
Biografi itu harus ditulis rapi lalu kami belajar mengedit teks bersama.

Both are acceptable. The comma makes the structure clearer by separating the two clauses, similar to English.

What is the difference between kami and kita, and why is kami used here?

Both mean we, but:

kami = we (not including the person you’re talking to)
kita = we (including the person you’re talking to)

Using kami implies:

The speaker and some others learned to edit text together, but the listener was not part of that group.

If the listener was included, you would say:

…, lalu kita belajar mengedit teks bersama.
= Then we (you and I and others) learned to edit text together.

Why is it belajar mengedit and not belajar untuk mengedit?

With belajar (to learn), the usual pattern is:

belajar + [verb]

So:

belajar mengedit teks = to learn (how) to edit text

Belajar untuk mengedit is grammatically possible but:

sounds more formal or heavy
is less common in everyday speech

Normal, natural forms:

Kami belajar mengedit teks.
Mereka belajar menulis.
Dia belajar berbicara bahasa Indonesia.

How is mengedit formed, and is it the normal word for “to edit”?

Yes, mengedit is the normal, everyday verb for to edit (especially texts, documents).

Formation:

root: edit (borrowed from English)
prefix: meN- (here becomes meng- before a vowel)
edit → mengedit = to edit

Examples:

Saya mengedit artikel ini. = I’m editing this article.
Dia mengedit naskah buku. = He/She edits the book manuscript.

Why is it teks (singular) and not teks-teks or something like teks itu?

Indonesian often leaves nouns unmarked for number if plurality isn’t crucial.

teks can mean:

text (one) or
texts (more than one), depending on context.

So:

mengedit teks can mean edit text or edit texts.

You can specify if needed:

teks-teks = texts (plural, general)
teks itu = that text / the text
teks-teks itu = those texts

In the original sentence, the exact number isn’t important, so plain teks is natural.

What does bersama add, and how is it different from bersama-sama or bersama dengan?

Bersama means together / with (as a group).

Kami belajar mengedit teks bersama.
= We learned to edit text together.

Variations:

bersama-sama: emphasizes togetherness a bit more, but similar meaning.
Kami belajar mengedit teks bersama-sama.
bersama dengan [someone]: together with a specified person/group.
Kami belajar mengedit teks bersama dengan guru. = We learned to edit text together with the teacher.

In your sentence, plain bersama already clearly means the activity is done jointly by kami.

Who is actually supposed to write the biography in Biografi itu harus ditulis rapi? The sentence doesn’t say by whom.

In Indonesian passive sentences, the agent (the “doer”) is often omitted when:

it’s obvious from context, or
it’s not important, or
the focus is on the result / requirement.

So Biografi itu harus ditulis rapi simply states the requirement:

That biography must be written neatly.

Depending on context, it could mean:

the students must write it neatly,
we must write it neatly,
the author must write it neatly, etc.

If you want to mention the agent, you can add oleh:

Biografi itu harus ditulis rapi oleh kami.
= That biography must be written neatly by us.