You can go to craft store like Hobby Lobby, or Michaels's or someplace that does custom framing. You'd have to either bring in the picture or the dimensions and they can make a frame for you. Either that or try doing it yourself. There are websites for the do it yourselfers. Sorry, hope I helped.

You can have it framed just as you would frame a painting on a stretched canvas or any otherr work of art. It's very commonplace for artists to paint on boards. They are looking for a stiff support that is lightweight and not as easily punctured like a regular canvas is
Just bring it to a frame shop, if you won't be doing the framing yourself or if the painting is a standard size (16x20,18x24,24x36 etc) you should be able to find readily available premade frames at hobby/craft stores like Michael's A.C. Moore etc.
No big deal that it is on a board. Really.
But just remember that if the artwork is an oil painting NOT to place it behind glass!