Buttonholes....Help!

[deb4566]

It's me again! You helped me shape the raglan sleeves, and join them to the body..now I need help with a buttonhole. I checked the videos but it is not the same pattern.

Pattern calls for K1, P1 rib. Here is what it says:
1st row: (RS) Rib across 4 sts. Cast off 2 sts. Rib to end of row.

2nd row: Rib, casting on 2 sts over cast off sts.

I have no idea what that means!! Can you all help me one more time?????