My name is long, iI live in paris and iI am an engineer web.

Whenever you use “I” it needs to be capitalized

I had studied eEnglish in the school, but iI had allve forgotten everything.

“English” is the name of a language and a proper noun, so it should be capitalized. “I had all forgot” is grammatically incorrect. “I have forgotten everything” is correct.

I want to restudy eEnglish again.

“Restudy” is not a word, so you’d use “study again”

I havn'te no idea how to restudy eEnglish again.

“Haven’t idea” is incorrect. The grammatically correct version is “I haven’t an idea” but “I have no idea” sounds more natural.

My name is lLong, i. I live in pParis and iI am an engineer web/ a web designer.

Names are usually capitalized, like "Long" or even names of places like "Paris". Not sure what "engineer web" is, but maybe "engineer" or "web designer"? Because "engineer" starts with a vowel, you should use "an" instead of "a".

I had studied eEnglish in the school, but iI had all forgotten it all.

Spelling correction like "studied" and making sure the tense matches for "had studied" and "had forgotten".

I want to restudy eEnglish.

I havn't idea how to restudy englishdon't have any idea how to start studying English again.

Or you could also say "I haven't got an idea". "Restudy" isn't really used so maybe just phrase it like "starting again".

First jJournal Entry

My name is lLong, iI live in pParis and iI am a web engineer web.

I had studied eEnglish in the school, but i had allve forgotten it.

I want to re-study eEnglish.

I havn't idea how to restudy englishBut I don't know how.

(My) First jJournal Entry

(1) In titles, we typically capitalise every word. There are exceptions to this, but I don't think you need to worry about them now.
(2) Just "journal" would refer to a whole collection of journal entries. To be more precise, you can write "journal entry".

My name is lLong, iI live in pParis and iI am a web engineer web.

(1) If you meant that your family name is "Long" (i.e. 你姓"Long"), then "Long" must be capitalised, as it is a name. If you meant that your name is long (i.e. 你名字很长), then your original expression is correct.
(2) "I" is always capitalised.
(3) Since "Paris" is also a name, in this case the name of a city, it is also capitalised.
(4) The term is "web engineer".

I had studied eEnglish in the school, but iI had all forgotten it all.

(1) "English" is capitalised, because it is the name of a language.
(2) Using "the" before "school" is unnatural, because you've not yet specified a particular school in your writing. 用汉语举个例子吧，这也正是“我在那个学校学过英语”和“我在学校学过英语”之间的区别。
(3) Alternatively, instead of "I had forgotten it all": "I had forgotten everything."

I want to restudy eEnglish.

Alternatively, just to introduce you to more ways of expression: "I want to study English again." or "I want to pick English back up again." are also good.

I haven't any idea how to restudy englishstart.

(1) Alternatively: "I have no idea how to start." "I haven't any idea how to start" (my correction) is perfectly correct, though it might be a grammatical structure that's a little more advanced.
(2) I replaced "restudy English" with "start", just to avoid consecutive repetition of the phrase.

First journal entry

My name is long, i. I live in pParis and iI am a web engineer web.

I think it's more natural to say "I have a long name".

I had studied eEnglish in the school, but i had all forgotI've forgotten it all.

I want to restudy eEnglish.

I think 'restudy' is not as natural in this context. 'Restudy' is more used in the context of going over something again, like re-reading a chapter in a textbook or something. If you're talking about restarting a subject after a long time, then if it were me, I'd say "I want to start learning English again" or "I want to start studying English again"

I havn'te no idea how to restudy englishstart studying English again.

Alternatively, you can combine the two sentences like this: "I want to start studying English again, but I have no idea where to start."