you know I will make it

now it is 6PM in China,I am in the student hostel hall,just went back from the school where I learn oral Engliah.
I swear to the God that I can learn English well.I wanna be a businessman in the future and I will work harder and harder.

---------------------

If I had written this, I would say:

I know I'll make it

It's now 6PM in China, and I'm in the student hostel hall. I just got back from the school where I study spoken English. I swear to God I can learn English well. I want to be a businessman in the future, and I will work hard to become one.

In general, "wanna" is fine in informal usage, but I would avoid writing it, as it's acceptable to write "want to" informally. 

"Oral English" is understood, but I think "spoken English" or "conversational English" sounds more natural, as Katherine already pointed out above (I wish I could tag people; I hope she sees this, haha). 

We say "went back /to/", and "came back /from/". For example: "Last night I went back /to/ the school where I learned spoken English," but "This morning I came back /from/ the school where I learned spoken English."

We do capitalize God in English, by convention, so good job catching that! We don't say "the God", though, except in special cases. Here, the phrase is "I swear to God".

"I will work harder and harder" is actually not wrong, but it feels unfinished: Try "I will work harder and harder to become one", for example. 

Overall, well-written; just a few points on usage to remember and you're well on your way! 挺好的，继续努力！

Hello Eric~ below is my correction of your post. I hope you will find it helpful.

Green - explanation

Orange - a word I believe should be in the text

Red - correction

---------------------------

you(?) maybe you mean -> I know I will make it

Right now it is 6PM in China,. I am in the student hostel hall,. I just went back from the (you use the only if you mention school more times further, for the first time mentioning you don't use it) school where I learn oral Engliah spoken/conversational English.
I swear to the (you don't use the before God) God that I can will learn English well. I wanna want to (polite and proper writing if you want to be a businessman ^^) be a businessman in the future and I will work harder and harder hard to become one.