Corrected parts are in bold pink.

First notebook entry: Introducing myself

I have been learning the English language since 1986, because I want to make new friends in English-speaking countries, and I like this language so much.
My native language is German, and I grew up in Austria. I enjoy music, esp. rock and metal, and Im an '80s fan. My interests and hobbies are: music, traveling, writing emails, fashion, Bon Jovi, hard rock, metal, concerts, cooking, meeting friends, singing, movies, tv series, vampire diaries and much more.
I have been married since 2004 to my husband Gyuszi; he has Hungarian roots.
I have one sister who is living in Germany. My sister is married and has two small children.
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A few notes: all proper nouns are capitalized in English, which includes the names of the languages themselves. This is almost the exact opposite in German from what I'm aware (where all nouns are capitalized except the names of languages).

Further, regarding how to write a decade in English: an apostrophe should only be used with a noun if the noun is possessing an object (i.e. Wesfall), and it shouldn't be used with any pronouns. For example, "Steve's boot" is correct, as is "his boot", but "it's boot" is never correct, nor is "many boot's". A lot of native English speakers write decades as 90's or 50's or 80's or whatever, but it's just not correct. The apostrophe in that case should go at the beginning, as they are contractions from 1990s/1950s/1980s.

Lastly, just as a minor nitpick, "little children" is an uncommon way to speak. It's not incorrect, per se, but "small children" is more accurate. The reason for this, at least in American English (I cannot comment on British/Canadian/Australian English, but I doubt it's different there), is that "small children" is an indication of age (similar to "young children"), while "little children" is an indication of size (similar to "short children"). Again, it's a very minor nitpick, but I figured I'd point it out.

Your other errors were basically minor punctuation things (something that most people on the internet generally disregard even if they know what they're doing).

And of course, welcome to italki!