If you breed a Pastel to a Spider each egg with have a:
25% chance of being normal
25% chance of being a Pastel
25% chance of being a Spider
25% chance of being a Bumblebee (Pastel and Spider)
In order to figure out what the outcome is depends on if you are working with Dominate, CoDom or recessive genes. To understand those I'd recommend checking out this thread: http://ball-pythons.net/forums/showt...Basic-Genetics
And for figurering out what to bred its really comes down to personal preferance. Look up pictures of morphs
Here is a good website of morph pictures:
http://www.worldofballpythons.com/morphs/
Or get a book with lots of morph picutes:
http://www.bigreptileworld.com/desig...s-2010-1-p.asp
This book lists tons of BP base morphs and what combos you can make with them.
See what you like and start breeding!
If you want to figure out what morphs are worth and what combo's you could bred for the most profit check out the BP market: http://market.kingsnake.com/index.php?cat=32 to get a better idea of what each morph is worth.