Rejoin Yarn?


I’m currently knitting a keyhole scarf for a 3 year-old, but I knit one side of the keyhole bit, and then it says ‘rejoin yarn’ to do the other side. How excatly do I do this?

It says:
Work Slit even in pattern on first 8 stitches for 3 ½ inches and place stitches on holder. Join yarn to remaining 8 stitches and work even for 3½ inches, then work across all 16 stitches


You can just start knitting with it and weave in the ends later.