Premier jour pour learning frenchd'apprentissage du français

Aujourd'hui, je me preépare pour de mon examen.

"to prepare" is "SE préparer" when the you "prepare yourself"

CJe commencon derai le 15 Sseptembre.

"commençons" would mean "let's begin"
Month names aren't capitalized

Premier, je lisèrement, je vais apprendre des verbes.

This wasÇa m'a été recommeanded by one of the youtuberé par un youtubeur/vidéaste.

"ça" would refer to "apprendre des verbes" (just to make sure this is what you meant)
"Youtubeur" is a widely used word, but there's also a purely French alternative, which is "vidéaste"