Honestly - it's the same process as any other guy;
Just because he white doesn't mean suddenly the game has completely changed lol;
You have to court the guy, get to know him, be flirty / friendly, and if he likes you back, you'll know.
It's as simple as that.
Keep in mind - some white guys like black girls, some don't - the phenomenon is a lot lower as it's more common for one to be attracted primarily to their own race:
But they are out there, lol take my word for it :P
Now the thing about High school though - is that a of kids haven't figured out what exactly they like yet; like I remember I had a really strong attraction for white / Hispanic guys - but I didn't dare pursue them because one they made me extremely nervous - and two I wasn't even sure if I was suppose to like them - if that makes sense.
Like look at it from a white dudes perspective; he goes home to his same race parents, his friend's date in their own race, society communicates that it's normal to be same race - even though he may have this mad attraction for women outside his race, being a teenager, he probably hasn't come to terms that it's okay -
It' happens in High school - but very rarely. There were a few interrracial couples at my school - majorly black guys dating out - but everyone else pretty much kept to themselves.
So don't stress about it - I know it's a bit frustrating, but just focus on school and creating your success for this world;
(not racist, it's just an expression me and my friend use from time to time)
I understand that this is your preference, and there is certainly nothing wrong with that, but when you say "looking for my white boy," it makes you seem desperate.
To answer your question, you have to get to know that guy. You'll have to test the waters with him. There might be a chance that he is more attracted to other races. There's also a chance that he might be attracted to black girls but not attracted to you. Basically, if one guy doesn't take a liking to you, don't dwell on it. Move on to the next one.
I date outside of my race a lot and next time you post don't post "Looking for my white boy" (makes you sound like you try and own people) plus this is not a dating site. However, you could just put something like "Would you date outside of your race or interacially."
The only way you will really know if a white guy is interested in you is if you talk to him or ask him what his prefereces are upfront. (its not likely that either one of you will).
I asked the last white man I dated if he would have came and talked to me if I had not talked to him. He said no...because he wouldn't think I was interested in him. He was pretty attractive to me and I asked if it was just becasue I was black. He was like yeah...its intimidating...I think for me the feeling was mutual.
Anyway if you like someone of a different race and you feel like they may like you too then try getting to know each other better. Hangout, Text, Talk all that good stuff...then when you feel more comfortable just ask the question "would you ever date outside of your race" by the time your comfortable talking to him, then its pretty easy. And just saying guys don't usually talk to you for long periods of time unless they are really just good friends or interested in you as more.
So figure it out. Or he'll move on. Color doesn't matter as long as you BOTH believe that. If you care what people think then well that relationship will go down the drain.
I wrote a lot because not many girls had much to say or can't comprehend what you were trying to say...so hopefully I made a dent.