Step 6: Adding a thumb hole
Lay one glove flat and lay your hand over it, as though you were wearing the glove, thus placing your fingers at the proper height. Stick your thumb out 90 degrees, and place one pin on either side of it. This is where the thumb hole will go. Transfer this mark to the second glove.
Going very slowly and following the instructions in your sewing machine manual, stitch a buttonhole in the glove between the pins indicating the thumb hole. Unfortunately, I cannot give more details than this, since each sewing machine sews buttonholes differently. Once you have sewn your buttonhole, use a seam ripper to rip open the hole between the lines of stitching. Try out the fit, then repeat with the second glove.