Rozzie,

Welcome! 

There are a number of different ways to add words, and it's probably easiest to add them after you've finished your crochet project.

Here are a couple of ideas: 

You can cross stitch the words onto your finished project. Words can be embroidered with back stitches, lazy daisy, satin, or other embroidered stitches. And if you'd like to crochet the words, you can surface chain stitch them on, very similar to an embroidered lazy daisy stitch.

I hope these methods help!