Well.. I have been asked out a few times.. But, I'm way too shy to go into a relationship.. I don't know why.. I reject..
I also want to marry the first man I date, if I ever do.. Well that just sounds silly..
Usually when I see the guy I like, my face goes really hot.. I'm still in high school.

I don't know what to do..

Meii,
Many kids feel under pressure to be in a relationship during high school. Most important is that you feel confident within yourself. Meii, your wish to marry the first guy you date is a nice idea and not silly, but very unrealistic, unless there is someone who you have known for a very long time and whose family knows your family and you both feel the same for each other. Even so, you never know... your wish might come true.
The guy who you mentioned, is this someone you know well?

You know you can go out with a guy without being in a dating relationship.
When you are ready for that, it will happen. You have plenty of time for that.