The F1 status becomes sensitive after 911, and it might take very long time to get your transfer approved. Some school may accpet guest student or visitor under relaxed conditions, however, the credits you earned are still good when you get into formal programm. So, check with your school to see if they accept guest student or visitor or anything like that.
Don't try to do the trasnfer in the dark, the international student office (ISO) of your school is suppoed to help you.
The official website you asked is from USCIS (formerly INS, then BCIS, now USCIS)
http://uscis.gov/graphics/formsfee/forms/index.htm
The ISO of your school should have all the forms, go ask for help.
In the statement of purpose, you need to indicate why you want to go from F2 to F1. Why you didn't apply for F1 visa before you came to US ? And what's the reason you think they will believe you will go back to China after you got your degree.
Since your spouse is F1, there must be somebody ther knows all these or even their ISO. It sounds complicated. But not really after you figured out all the documents you need, and what you need to do.