Don't take those e-mails too seriously, you'll continue to recieve more and more as you go through high school, and even more when you take the SAT. Remember that colleges are about money first, education second. Those e-mails don't mean you're guaranteed a spot at the school or anything like that, they're just advertisements. I'm a junior and have got a whole shelf on my desk for nothing but college mail and a whole e-mail account for colleges (I write the e-mail address wherever I on any forms I expect to get college e-mails from: SAT, ACT, etc). I suggest anyone else starting to go through this process does the same. When you start to get your colleges nailed down, go through your stack of mail and find whatever mail you have from those colleges, you can also use the search feature on your seperate e-mail. What you don't want to do is throw away all of the mail and delete all of the e-mails (or let the e-mails overwhelm your normall e-mail address) because they can be useful in the future if you keep it organized. I'm just starting to go back through it all and it's pretty amazing how fast it adds up. As I'm going through the mail, I'm finding that I've received mail from Harvard, tons from Brown, and a bunch of other high end colleges that I KNOW I won't be able to get into, so again, don't take them any more seriously than you would a flashy commercial.
I don't mean to put you down or anything, but it definitely is a learning curve, and a bit overwhelming at first and I know I took (and take) any advice I can get on the whole thing. Good luck!