rainbow crochet squares

Alright so not quite a rainbow, but don't the squares look lovely arranged in colour-order?


I'm not using a pattern for my patchwork blanket, so it could go anywhere. The nice thing about that blanket is that it's meant to look random. 


I made a load of the smallest squares (approximately 37 of them, but I will be making more), then moved on to the biggest squares. I need to sew in the ends though and I don't have a clue how. Anyone know of any good tutorials?