Here's the deal. Im n middle school and there's a girl I've liked for a while and I want to Ak her out. Idk if she likes me rite now but she has within the past year.we are going to be on the same beach vball team this summer so I'd want us 2 last at least 2 fall. What do I do?

First correct your grammar so that it is a little more understandable.
Second here's a good tip if you and her are friends that eat lunch together. Once you got your lunch go sit down a little close to her. If she moves away just play it cool and say something like "ohh sorry didnt mean to get all up close and personal" and if she just shifts to adjust a little, she doesn't mind being cozy with you. :) hope this helped.

Why do you want her at least until the fall and what does going out mean when you're in middle school?
Be friends with her. Friendships tend to last when they are real.

Does anybody have anything else?

Relax and try being simply friends.
There's no need to go rushing head long in to the whole boyfriend/girlfriend thing.
These things will happen in the fullness of time.
Just enjoy being a kid.

When or where at school is a good time to get her undivided attention long enough to ask her out?

Anyplace and every place. It doesn't have to be a big production.

I'd keep it casual.

Curlyben is right and I know you may not like my comment, but at your age you should not be rushing into the whole dating thing. Relax and take it easy while your in middle school.