I have sent enough cross-stitches to the framers to have a rough idea how to do it myself. So I bought this photo frame from Ikea to mount my latest cross-stitch of a sailing ship.
(1) Glue down the cross-stitch onto the back board, leave to dry.
(2) Cut the border to fit the picture. The edges will be rough because you don't have specialized tools like a framer. So I wrapped it with scrapbooking paper and it worked out fine. You can also use fabric.
(3) Stick on scrapbooking stickers or embellishments. I didn't do this because I wanted to leave it to the recipient to personalize.
(4) Put all the elements together to make a beautiful framed cross-stitch that will rival any professional framer.
* I did cut 2 fingers in the process though, not used to working with sharp metal edges.