There is a video about wrapping stitches on this page. Scroll down till you find it. I don’t know if it covers picking up the wraps, but it should.
If you are on a knit row you work to the stitch that has wrap around it (it will look like a horizontal line going across the bottom of the loop on the neede). Use your RH needle to go under the wrap and then knitwise into the wrapped stitch. Knit them together.