After you have separated your glove thumb and hand with a stitch holder, you’ll knit the hand of the glove. Then, you will want to make the thumb using the live stitches you have saved. To work the live stitches…
Weave in Loose Ends of Mittens, Part 3: The Thumb Base
Knit Off Stitch Holders with DPNs - Knitting a Glove Thumb - PurlsAndPixels
Knit Off a Stitch Holder in the Magic Loop – Glove Thumb - PurlsAndPixels
Knit Off Stitch Holders with DPNs - Knitting a Glove Thumb - PurlsAndPixels
How to Use a Stitch Holder - How to Transfer or Slip Stitches onto a Stitch Holder
How to make a Knit Stitch, free knitting lesson from PurlsAndPixels
Knitting Stitches Off a Stitch Holder with Double Point Needles - Making Mitten Thumbs on DPNs
Knit Off a Stitch Holder in the Magic Loop – Glove Thumb - PurlsAndPixels
Knitting and so on: All Fingers and Thumbs