Sakura8 is giving you some good instruction. Also just as FYI since you seem to be new with bettas...once he is in a warmer environment, his natural colour will probably deepen. So if you see any colour change such as this, it's ok. Keep an eye on the whitish areas.
Try not to over feed. When bettas are well, they eat and eat. I have lost a couple from constipation that is caused by overfeeding. As well, I had read elsewhere that bloodworms are definitely only to be used as a very occasional treat as they will cause constipation (anyone else more knowledge about this fact?)
Good luck with helping your new fish.