Rows like this always sound more complicated than they are. If you go to the Free Videos at the top of the page, you'll find the M1-R and M1-L as well as the yo demonstrated. Purl 1 through the back loop is shown on the Glossary page (http://www.knittinghelp.com/video/pl...k-loop-english
The "slip next st knitwise, slip st back to LH needle purlwise," is just a way of reversing the orientation of the slipped stitch. Slip it to the RH needle as if you were going to knit it and then slip is back to the LH needle purlwise. The slip purlwise is also shown on the Glossary page.