I would like to carry out a non-linear static analysis but considering my structure's natural modes, and I would like to know how I can set this up in the SAP2000 software

I have tried to consult the user manuals but I have not found anything about the modal pushover analysis.

In the definition of loads for the non-linear static analysis (as show the image below) , there is a section where you are asked to define the modal loads, but I don't really understand what this image is about, and the concept.

I would like you to help me define the modal loads and to understand the concept or basically I would like you to help me perform a pushover modal analysis on SAP2000.

thank you