You might start by exploring some of the dealers' web sites, such as Black Jungle and Saurian, although there are others that are reliable dealers. These are simply the only two I've dealt with so far. They have photos, care sheets, species names, etc. You can also do a search under "Dendrobates," that will get you to a lot of sites where you can look at photos and care sheets.
There are many different dart frog species with the color combinations you have mentioned, so it is hard to give you information based on color alone. Blue and black can be either D. auratus or D. azureus, which require somewhat different conditions. D. auratus get along in groups, while D. azureus get along best in mated pairs. The yellow and black could be a number of frogs, but the most popular is D. leucomelas, which are great in groups as beginner frogs. If you get familiar with them generally by a search of this sort, then ask more specific questions, we can probably help you better. I really hate telling new people to the hobby to do a search, because what you want is some personal help, but it really needs to be narrowed down a bit with some initial exploration, or we'd be going on forever, virtually writing a book.
There are some good books, by the way. For starters, I would recommend "Poison Frogs," Professional Breeders Series--W. Schmidt and F.W. Henkel for a start. It is somewhere in between a pet store "how-to" book and a tome of detail, and is still affordable. It's probably available through Saurian or Black Jungle. The link to a dircect online source is:
Link
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus