How do you sew two pieces together?
Anne
Sewing pieces together (like with the baby poncho)
Mattress stitch is the best way to go. I just finished seaming the side of a sweater and it just reminded me how wonderful it is!! If my camera were home I’d take a picture and show you. Can you tell I’m pleased how well it came out? 
If you haven’t found it yet there is a wonderful video on this site http://knittinghelp.com/knitting/basic_techniques/misc.php. Scroll down to Finishing and click on Mattress Stitch.
If it weren’t for these wonderful videos I don’t know what I would have done.