I am almost done with my first board bow. I am kinda chalking this on up as a learning experience and putting everything I learned toward my next one and just finishing this one up the best I can. It looks like it will be a shooter which is cool but my questions are.
It developed a deflex on bth sides from what I have read you can't fix that but what causes it so I know for my next one is it moisture?
Second what's the best way to seal this bow its red oak will any stain work or is there any specifics?
Third I built this primarily with a rasp and a file wanted to do it mainly by hand, but I wanna get some more tools for my next ones what are the musts that I should pick up.

Thanks guys you have all been really helpful in completing this.

Every bow will develop set, even the glass ones, to some extent. Your tiller and the way you chase the tiller will determine how much. Just take it slow, and make yourself a tillering gizmo. Do a search on here and find out how. That is the most valuable tool you can have. The wood itself does also contribute to amount of set, but unless its really green, it won't amount to much. You can minimize the amount of deflex by inducing some reflex into the stave at the beginning, so that when it does take a set, it really just takes out some of the reflex instead, leaving you with a straight, or almost straight bow afterward.
As far as finishing, stain is fine. Don't use a water based stain though. Use solvent based. Then a good polyurethane is fine. I'll typically use 3-4 coats of an oil finish on the wood first to soak in and seal the grain (sanding lightly in between), then 3-4 coats of the minwax spray satin polyurethane over that.
As far as tools, the gizmo first,  then maybe a draw knife or spoke shave would be handy, and possibly a small band saw for roughing out, if that's in the budget. But you can do it all with the draw knife, rasp, and file.

Don't forget to post some pics, no matter what it looks like. There's a wealth of info here for anyone who wants it. The guys on this site are top notch, and are always ready and willing to help.

Make the bow longer and wider to reduce set.  Use good wood.  Use dry wood.  Tiller carefully.

I have made somewhere between 150 and 200 bows and I could not make a bow with no set.

The best I can do on red oak is 2-3" of string follow from a straight stave.

If you start with reflex, your bow will still set but may not follow the string.  There is a distinction between the two.  Read Traditional Bowyer's Bible Vol. 1 - Design and Tillering and its follow up in Vol 4.