How to add skills, crouching, different looks to the existing Paragon assets?

Hello there! I’ve got a question on how to accomplish such difficult thing.
For example I’ve downloaded some paragon assets, I managed to import them, as well I managed to “play” with them! And now here comes my question, how would I add “skill” effect to it? Such as, if " player presses X, then a fireball will be created". I’ve tried to look inside vault cache directory, yet I didn’t find any 3D files.

This also applies to crouching animations.

Another question how would I make that function active? Such as “When C is pressed, perform crouching animation”.

Thank you so much !