Beginner Educational Resources
Any of the Stimson airborne radar books are good modern resources for general radar signal processing.
For more specific applications (basic STAP, EW, mismatched filters etc), you can look at Mark Richard’s book(s).
If your company has a library, check to see what radar books they have on hand; you may be able to get these for free.
Last, MATLAB has entire packages based around radar systems and plenty of examples that use them. If you have access to a MATLAB license, those might be good to check out as well.