Sewing seams for garter stitch

[KVCharles]

Hi!
Thank you for your previous help with sewing seams...I am just stuck on this part of the pattern...

I need to sew garter stitch seams for a sweater...I understand how to do mattress stitch for stockinette but how do you do it for garter?

Thank you in advance for your help!

[knitqueen]

There's good explanation and illustrations at the Lion Brand webiste:
http://learntoknit.lionbrand.com/cgi...eyarn&faqKey=1