Help!! Trying to figure out how to attatch sleeves to a sweater

The directions read:
Sew shoulder seams. Sew in sleeves placing rows above markers along unworked sts of Back and Fronts to form square armholes. Sew side and sleeve seams.

So, my question is, what is it telling me to do...Am I to crochet them in somehow or stitch them with a tapestry needle. I'm thinking it might be a little bit of both. I've searched the web for a tutorial and I've studied it myself, and I just can't come to a conclusion. I know this has to be simple...can someone help??