This is a classic garter stitch booties pattern with the addition of a turned down bubble stitch cuff, knit in DK weight yarn.
The booties are knit from the cuff down.
The pattern includes instructions for both knitting flat on 2 straight needles and knitting in the round. Just choose whichever option you are most comfortable with.
The pattern includes plenty of stage by stage photos and there is a whole page bubble stitch photo tutorial at the end.

The bubbles on the cuff look best when knit in an elastic yarn such as merino wool.
I would not recommend cotton or linen yarns if you wish to show off the bubbles at their best.