Learn to Crochet!
Crochet Gif Tutorials: Changing Colors (and Crocheting Over Ends)
This can be fiddly, but you will get the hang of it!
In this example, the project is made up of rows of single crochet (sc) stitches. But this works for other stitches too. The overall rule is to ‘use the new color when doing the final ‘pull through the loops on your hook’ of the last stitch in the previous color.’ (Let me know if you think a separate tutorial for a different stitch would be useful, though!)
Crocheting over the ends is by no means essential, if you find it easier, you can ignore that step and go back and weave the ends in when you finish the project. But let’s be honest, everybody hates weaving in ends, so this is a great trick to master! Keep crocheting over the ends for the next few stitches of the row, until they’re nicely secured. Then snip off any excess.
For some extra notes on crocheting over the ends, please see this post.
(Also yes, I guess the editing process has made this green yarn slightly yellowish!)