Hi everyone! I'm new to knitting, and new to this forum

I just started my first big project, a stuffed kangaroo. I'm finishing up the head and the pattern says to do this:
"Break off yarn, run end through rem sts, draw up tightly and fasten up securely"
How do I get the yarn through the stitches, and what's the best way to fasten it after?
The next instruction is for the back, and says "With right side facing, knit up 18 sts evenly along side of boucle rows of head."
I have absolutely no idea what this one means... please help!