Re-Attaching Yarn

I am working on a pattern that called for casting off some stitches and then fastening off. I did that and now it is asking to rejoin the yarn and purl the remaining stitches. How do I re-attach the yarn when there is no tail like adding another skein?? :whoosh:

Leave a tail of a few inches from the yarn you’re going to attach, and just start knitting with it. When you’ve done 2 or 3 stitches, tie that tail you left to the working yarn (in other words, to itself, but now because of the 2 or 3 sts, it’s got something to anchor to) and you’re set. Make sense?

Use another yarn end, either from the other end of the skein or from a different one. Then start knitting with it leaving a couplethree inches for the tail.

THANKS!!!

THANKS!!!