Having trouble enrolling for summer semester online.?

i am trying to enroll for summer semester online and it seems to be harder than i thought. I add the classes i want and then it tells me i am not a fla resident, not sure why, also it says i cant register until some date that i cant see for some reason, and the classes i want start in less than a month and have very few seats left, is it past the date or before?. i only want 15 credits and plan to acquire them in summer and fall semesters. and am paying cash money. should i go to the school before there are no open spots left? because i dont have alot of free time and was hoping for online classes.