kono botan wo osite kara, pasuwaado wo nyuuryokusite kudasai.

You’re right: Japanese is normally written without spaces.

So the standard written form is:

このボタンを押してから、パスワードを入力してください。

Spaces are often added in textbooks or beginner materials to make it easier to see the parts of the sentence. They are just a learning aid, not normal spelling.

この means this and must come before a noun.

So:

• このボタン = this button

A common beginner confusion is mixing up:

• この = this + noun
• これ = this thing

So you say:

• このボタン = this button
  but not これボタン

を marks the direct object of the verb — the thing that receives the action.

Here, the verb is 押す meaning to press, so the thing being pressed is:

• このボタンを = this button as the object

So the structure is:

• ボタンを押す = to press the button

This is very similar to how English uses word order to show the object, but Japanese uses the particle を.

押して is the て-form of 押す.

The て-form has several uses, and here it is being used to connect actions:

• 押してから = press, and then... / after pressing...

So:

• 押す = press
• 押して = pressing / press and...

You need 押して here because the sentence is linking the first action to what comes next.

〜てから means after doing... or do ... and then ...

So:

• 押してから = after pressing
• 入力してください = please enter

Together, it shows the order clearly: first press the button, then enter the password.

This pattern is very common:

• 食べてから、勉強します。 = After eating, I’ll study.
• 家に帰ってから、寝ます。 = After going home, I’ll sleep.

Yes, that is possible, but the nuance is a little different.

• 押してから、パスワードを入力してください。
  = Press it first, and after that, enter the password.

• 押して、パスワードを入力してください。
  = Press it, and enter the password.

Both suggest sequence, but 〜てから makes the order more explicit. It strongly emphasizes that the second action happens after the first one is completed.

So in instructions, 〜てから is often very natural.

Yes — 入力 is originally a noun meaning input or entry, but it is very commonly used with する to make a verb:

• 入力する = to input / to enter

In this sentence, that verb appears in て-form:

• 入力して = entering / enter and...

And because パスワード is the thing being entered, it takes を:

• パスワードを入力する = to enter a password

This noun + する pattern is extremely common in Japanese.

ください makes the sentence a polite request:

• 入力してください = please enter

So:

• 入力する = to enter
• 入力して = enter and...
• 入力してください = please enter

This is one of the most common ways to give polite instructions in Japanese, especially on signs, screens, manuals, and customer-facing messages.

It is more polite and softer than a plain command.

It is an instruction or polite command/request.

〜てください is polite, standard, and very common. It is appropriate for:

• instructions on machines
• app or website messages
• directions to customers
• general polite requests

It is not especially soft or warm, but it is not rude either. It is neutral-polite.

If you made it more direct, it might sound stronger:

• 入力しろ = Enter it!
• 入力せよ = Enter it. / Do enter.
  These are much harsher or more formal/command-like.

So 入力してください is the normal polite choice.

Japanese often omits the subject when it is obvious from context.

In an instruction like this, the unstated subject is basically you:

• (あなたは) このボタンを押してから、パスワードを入力してください。

But Japanese usually does not say あなたは in this kind of sentence, because it sounds unnecessary.

So the sentence naturally means something like:

• Please press this button and then enter your password.

with you understood from context.

The comma helps separate the first action from the second and makes the instruction easier to read:

• このボタンを押してから、パスワードを入力してください。

It is especially common in written instructions. Japanese punctuation is somewhat flexible, so you may also see the sentence without a comma, but with a longer sentence like this, the comma is very natural.

Yes. Both are very natural here.

• 押す is the normal verb for pressing a button.
• 入力する is the normal verb for entering text, numbers, passwords, and other data into a device.

So this sentence sounds exactly like the kind of instruction you would see on a machine, kiosk, website, or app.