Hello,
We have a lot of step-by-step tutorials and related forum posts that should help you start:
Corvid Tutorial: Adding Collection Data Search Functionality
https://www.wix.com/corvid/forum/community-discussion/filter-one-dropdown-by-another
https://www.wix.com/corvid/forum/community-discussion/changing-multiple-searches-in-wix-code-into-just-the-one-search
https://www.wix.com/corvid/forum/community-discussion/help-with-multiple-dropdown-s-to-filter-a-dataset-and-populate-a-repeater-with-results-using-wix-code
https://www.youtube.com/watch?v=EhXed0u6wh0
https://www.youtube.com/watch?v=r0DLqkRDJ34
https://www.vorbly.com/Vorbly-Code/WIX-REPEATER-WITH-MULTIPLE-FILTERS
https://www.vorbly.com/Vorbly-Code/WIX-REPEATER-MULTIPLE-FILTERS-WITH-RESET