Confused on pattern - cast on at end of knitted rows, increase at beginning of purl row

[Crista]

I'm a novice knitter working on my first sweater. The pattern says to knit to the end of the first row, cast on 3 stitches (front edge). 2nd row: Increase in 1st stitch purl ways, purl to end.

Can I cast on the same way I do when casting on my first row before beginning to knit?

I've seen videos of increasing in a purl row, but they only show it in the middle of the row, not the end.

Any help would be greatly appreciated!!!