Hi, welcome to the forum! There's lots of information on breeding in the breeding section of the forum. There is also a search feature up at the top of the site if you're looking for a specific topic.
If you breed a butter to a diffused, all the babies will be normals unless the parents are carrying hets.
You may also like corncalc.com. It's a great tool for calculating what offspring you could get from a pairing.