Assuming you are asking about setting machining data, here is the high level view...
First, you need to have a part material on your setup or geometry group, a tool material on your tool, and a cut method on your method. If you want to try OOTB data, I recommend you use the entries that start with "HSM" near the end of each list.
Now in a milling operation, in the feeds and speeds dialog, hit "Set Machining Data". The system looks at the 3 items above, plus your tool dimensions and machine rigidity, and searches the library for close matches. Based on what it finds, it sets the speed, feed, cut depth, and stepover. It's not just a simple interpolation either - we look at the tool rigidity.
To add or edit the entries in the library, go to Tools --> Edit Machining Data Libraries.
The idea is to find what works in your shop, and then save it. The more you save, the more accurate future calculations will be.
Once you have everything set up, turn on the customer default to always set maching data. Then when you create an operation, it's all set. Change something (like tool length for example) and the settings update.