Trying to write in Japanese

Hello!

I tried to write some sentences in Japanese, but they might have many mistakes, since I have no practicing in writing. I said in the text I'm learning Japanese since some years ago, but in fact it wasn't a continuous learning and it was never writing-oriented.

私はブルノです。２５歳のブラジル人です。
I 'm Bruno. I'm a 25 years old Brazilian.
(and how could I put it all in one phrase?)

何年か前から、日本語が勉強します。
I'm studying Japanese since some years ago.

でも、上手ではありません。
But I'm not good at it.

実は、このテキストは日本語で初めて書くテキストです 。
Actually, this text is the first text I'm writing in Japanese.
(ok, this is not the first text, but I wanted to write this phrase)

Hope to hear tips from you, Thanks!

Good try, Bruno!

私はブルノです。２５歳のブラジル人です。
I 'm Bruno. I'm a 25 years old Brazilian.
(and how could I put it all in one phrase?)

Click to expand...

→私はブルノ、２５歳のブラジル人です。
I'm Bruno, a 25 years old Brazilian.

何年か前から、日本語が勉強します。
I'm studying Japanese since some years ago.

Click to expand...

数年前から日本語を勉強しています。
何年か前 is also good. 数年前 is more common and sounds natural, though.
が is a particle to mark a subject.
For object, you use を.
te-form + いる／います is used to express the on-going thing.

でも、上手ではありません。
But I'm not good at it.

実は、このテキストは日本語で初めて書くテキストです 。
Actually, this text is the first text I'm writing in Japanese.

Click to expand...

The above is perfect!

...If anything, you can use the word 文章（ぶんしょう） for "text".
テキスト in Japanese usually used for textbooks rather than a group of sentences.

Thank you for helping, undrentide-san! So I made it right the last sentence. Ureshii =). You motivated me to write a little more... I'm posting here the entire thing (which I wrote after confirming that phrase was ok).
Here we have a larger text:
こんにちは、ちゃ様！
Hello, Tcha-sama!
これは私、ブルノです。ちゃさんはどうですか？いい暮 らしだといいのですが。
This is me, Bruno. How are you? (Can I use this phrase instead of 'genki desu ka'?) I hope you life is fine (good).
今度、日本語で書いています。実は、この文章は日本語 で初めて書く文章です 。
This time I'm writing in Japanese. Actually, this text is the first text I'm writing in Japanese.
たとえ数年前からちゃさんの言語を勉強しても、まだ上 手ではありません。頑張ってる。=)
Even studying Tcha's language since years ago, I'm still no good at it. But I'm trying / I'm giving my best.
‥今は、眠らなくてはいけません。眠たいい！（ー・ー）‥
... I have to sleep now. I'm sleepy!
このメッセージを読んでくれてありがとう。ああ、イースターおめでとう！^o^
Thank you for reading this message. Aa, happy Easter!
ちゃさんのブラジルの友達から、
ブルノ
From your friend from Brazil, Bruno