1st question (what to do with your cast on tail)
hare are a few options:
option 1: Knit your first stitch, then pick up the tail along with your knitting yarn and knit 3 stitches with both pieces of yarn. Then drop the tail yarn and continue to knit with the normal yarn. Later -- when you're done with the piece you can chop off the tail yarn and it won't unravel because you've knit it together.
option 2: Just leave the tail and use it to sew a seam (assuming you have a seam to sew on the side of the knitting that the tail is on.
option 3: Weave the tail yarn into the piece after you're done
2nd question (how to find a knitting group)
I found a knitting group in my area on meetup.com
check to see if any groups are near you: All Knitting Meetup Groups