How do I attach the sleeves

I am knitting Redhearts pattern “Baby Cardigan & Hat” # WR2171

I have knit all the pieces and am ready to put it together but there are no instructions on how to attach the sleeves.

Do I sew the seam in the sleeves first then inset the sleeves into the main body of the sweater. If so, what kind of stitch would I use to attach the sleeve?

Is there a video of this process?

Would appreciate anyones help.
Linda In California

Sew the sleeves into the body first, then seam the sleeves and the seam of the body. Mattress stitch is generally used and there’s a video on the Tips page under Finishing.