To start, take a look at these resources on conditional value lists. There's a log of overlap between the first two so you can read one and skim the other.
Forum Tutorial: Custom Value List?
Knowledgebase article: http://help.filemaker.com/app/answers/detail/a_id/5833/kw/conditional%20value%20list
Hierarchical Conditional Value lists: Conditional Value List Question
The demo file lets you download and examine actual working examples of conditional value lists. Since you have FileMaker 12, open this file from the File menu to get a copy that is converted to the .FMP12 file format.
The last thread discusses how you might set up a chain of conditional value lists where the value selected from one conditional value list controls the set of values displayed in the next conditional valu list.
Feel free to post follow up questions here if those links aren't enough to get your value lists working correctly.