Where to add custom JS?

Hello there! I am a newbie to wp, but so far I getting the way how this works. Love your plugin btw, and I’ve found couple of features I’d like to add to TablePress. I’ll try the best I can to describe what I want… First one is, how and where i should include this code:

https://www.datatables.net/examples/api/multi_filter_select.html

so i can get that search with select options ABOVE the table alongside with allready active text search included with plugin. Should I need to include that JS library also?

and second:

https://jsfiddle.net/p9mtqhm7/52/

also where to put it, to add this cool feature of expanding and colapsing table headers to make my table easier to read?

Thanks!