Joining two strips together - blanket

Ok, i’m new, and i’m making a blanket for my little brother, its very nice so far with the large ribbing. i didn’t know how the circular needles would’ve prevented this problem until i was reading these forum questions…

i will b making 3 strips and putting them together…anyone know the way to stitch them together? like down the vertical edges?

my next blanket will b on circular needles i promise :smiley: