Во время вебинара я делаю запись в блокноте.

Во is just a pronunciation-friendly variant of в. Russian often uses во before certain consonant clusters or sounds that are awkward to pronounce.

So:

• в школе
• в доме
• but во время

You should learn во время as a fixed expression meaning during.

Because во время requires the genitive.

So the pattern is:

• во время урока — during the lesson
• во время встречи — during the meeting
• во время вебинара — during the webinar

The dictionary form is вебинар, and the genitive singular is вебинара.

It is a prepositional phrase meaning during the webinar.

Breakdown:

• во время = during
• вебинара = of the webinar

Literally, it is closer to in the time of the webinar, but in normal English we translate it simply as during the webinar.

Russian often uses certain noun + verb combinations where English prefers a simple verb.

Here:

• делать запись = to make a note / make a запись

So я делаю запись literally means I make a note.

However, for everyday Russian, this phrase can sound a little formal or specific. Depending on context, Russians might more naturally say:

• я записываю — I write down / I note down
• я делаю записи — I take notes
• я делаю заметки — I make notes
• я делаю пометки — I jot down notes/mark things

So your sentence is grammatical, but it may sound like making a note rather than generally taking notes.

This is an important nuance.

• делаю запись = I make a note / a record / one entry
• делаю записи = I make notes / I am taking notes

So if you want the idea of continuous note-taking during a webinar, делаю записи may sound more natural than делаю запись.

Singular запись suggests one particular note or one recorded entry.

Because в can take different cases depending on meaning.

Here it means in the notebook, indicating location, so Russian uses the prepositional case:

• блокнот → dictionary form
• в блокноте → in the notebook

Compare:

• в блокноте — in the notebook (location)
• в блокнот — into the notebook (direction, much less likely in this sentence)

So в блокноте answers where?

Not in this sentence.

• в блокноте = in the notebook
• в блокнот = into the notebook

Since the sentence describes where the note is being made, в блокноте is the normal choice.

If you said я записываю это в блокнот, then в блокнот could work because the wording suggests putting information into the notebook.

Yes, Russian often drops subject pronouns when the meaning is clear from the verb ending.

So both are possible:

• Во время вебинара я делаю запись в блокноте.
• Во время вебинара делаю запись в блокноте.

Including я makes the subject more explicit. It can sound neutral, or slightly more emphatic depending on context.

Because the sentence describes an ongoing, repeated, or uncompleted action.

• делаю = imperfective, focusing on the process
• сделаю = perfective, focusing on completion

During a webinar, if you are in the process of note-taking, imperfective is the natural choice.

Compare:

• Во время вебинара я делаю записи. — During the webinar, I take/am taking notes.
• Я сделаю запись позже. — I will make a note later.
  Here the focus is on completing the action.

The noun запись can mean different things depending on context:

• a note
• an entry
• a record
• a recording

But here в блокноте strongly suggests a written note in a notebook, not an audio or video recording.

So in this sentence, learners should understand запись as something written down.

No, Russian word order is flexible.

Your sentence is perfectly normal:

• Во время вебинара я делаю запись в блокноте.

But other orders are possible, depending on emphasis:

• Я во время вебинара делаю запись в блокноте.
• Я делаю запись в блокноте во время вебинара.
• В блокноте я делаю запись во время вебинара.

The original order is natural because it starts with the time phrase during the webinar, then gives the subject and action.

It is understandable and grammatical, but many speakers would choose a more natural everyday phrase if they mean general note-taking.

More natural alternatives might be:

• Во время вебинара я делаю записи в блокноте.
• Во время вебинара я записываю всё в блокнот.
• Во время вебинара я делаю заметки в блокноте.

Your original sentence sounds more like I make a note in my notebook during the webinar, possibly a single note, rather than broad ongoing note-taking.