Mk1 and Mp1 increase

I am starting to knit a sweater that is knit on the diagnoal. The directions say to cast on 3, next row Mk1, k1, Mk1, Next row Mp1, p3, Mp1. I am using yarn that is uneven and looks like it has a knot every 4 inches or so. I am confused how to to the Mp1. Some increase directions tell me you can only increase in the knit row. HELP! I want to finish the sweater before Christmas and can’t seem to get started!!!

To M1p. you need to lift the bar between the stitches with your left tip from the back. This way the little loop is in the front. Purl into it for the increase.