All right, you just finished the ribbing. You have 16 stitches on each of 3 different needles for a total of 48. You then worked 2 rnds even.
Rnd 1: On the first needle of the row you K8, M1, K8. Now you have 17 sts on that needle. Knit across needles 2 and 3 without doing anything special. You now have 49 stitches.
What you are going to be doing is increasing the gore (sometimes called a gusset), which is the place where the thumb will be later. All the gore shaping is on the first needle each time, then you just knit even across the other 2.
Do you know how to do the M1?
After the first round you knit 2 rounds even, no funny business.
Rnd 4: On the first needle K8, M1, K1, M1, K8. Now you have 19 on needle 1. Work the rest of the round. You have 51 altogether.
You keep working that way, increasing as they say on needle 1 each increase round and working even on the rest.
When you get to Round 23 you Knit the first 8 and then use a piece of scrap yarn and a tapestry needle to transfer the 15 stitches you increased for the gore onto your scrap yarn. After you move the stitches to the spare yarn use a backward loop increase to put 5 stitches on the end of the needle in your right hand. Then you knit the rest of the stitches on the needle, pulling the gap between the 5 stitches you cast-on and the first of the 8 stitches that are left.
Rounds 25-27 you follow the directions to decrease back down to 47 stitches so you can continue the palm.
Does that help?