If you are only doing a few stitches in each color, you can carry the unused yarn across the back--stranded or Fair Isle knitting.
If you have larger blocks of each color, you can use a long strand for each section--intarsia knitting.
Amy has video on both in the Advanced section.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry