My First (time of writing an) Italki Notebook.

I just joined (started) italki a few days ago. Although (So) I don't (still) understand the system yet, (But) I'm trying to write a notebook in order to have (get) my English corrected.
I'm studying English and (to speak fluently. I) want to be able to speak fluently, (English) just like a  native speaker. (English speakers do.) 
When I was a junior high school student, I started to learn English at school, but it wasn't practical English, only reading and writing.
So, when I communicate with people (in English) face-to-face, I can't speak any English.
Hence, (So) I started learning practical English a year ago.
It's so difficult, but I'm doing my best.

Your writing is, on the whole, very good. I have suggested a few amendments to help improve the flow of your sentences. 

My first time writing an italki note [the notebook is the place where you write the notes].

I just started using italki a few days ago. So I still don't understand the system yet, ["but" should follow a comma rather than a period] but I'm trying to write a note to get my English corrected.
I'm studying English to speak fluently. I want to be able to speak [English] like native [English] speakers do.
When I was a junior high school student, I started to learn English at school, but it wasn't practical English. Only reading and writing.
So, when I communicate with people in English face-to-face, I can't speak any English [or "I can't speak a word of it"].
So I started learning practical English a year ago.
It's so difficult, but I'm doing my best.

Practice makes perfect! :) 

My first time of writing an italki notebook.

I just started using italki a few days ago. So I don't still understand the system yet, but I'm trying to write a notebook to get my English corrected.
I'm studying English to speak fluently. I want to be able to speak English like native English speakers do.
When I was a junior high school student, I started to learning English at school.
But it wasn't practical English. Only reading and writing.
So when I communicate with people in English face-to-face, I can't speak any English. (or 'I can't speak well')  
So I started learning practical English a year ago.
It's so difficult.
But I'm doing my best.

Good job! ^.^