Mona premierère entrée de journal entree

ma = feminine possessive pronouns
Noun complements are introduced using "de" in French, although there are a few exceptions

Aujourd'hui je apprendre sur'étudie les verbes irréguliers.

The best translation of "learning about" in this context would be "étudier"
je+vowel => j'

C'est treès difficile.

Accents are mandatory in French (you can use a virtual keyboard for this, I recommend the Lexilogos one)

Je apprendre sur'étudie (aussi) le preésent tense.

C'est monLe français est ma langue préféré langue maintenant.

"c'est" would mean "the present tense is my favorite language"
As I suppose you mean French, you have to specify it