Sewing/hemming jeans is tricky but doable.
Make sure you have a needle for the sewing machine that's meant for jeans.
Try to get a scrap piece of jean and practice, practice and practice.
Look at the color thread of the jean and go get the color, just make sure it's meant for denim.
One thing I love is fusible hemming tape. It's thin, and you can role up the jeans where you want them, tuck the tape in the folds and just iron it and it fuses it in place. I hate pins and this works great for me. Try it on a sample piece to make sure is doesn't gum up the needle and sew.
I'm glad all is well.
