How to edit theme codes to insert a plugin tag

I tried to use an ad inserting plugin to automatically add (Google AdSense) ads in category loop pages and search result pages, but was told I’d need to edit theme codes to insert plugin tag. I use a premium theme called Socialize, and the plugins I’m hoping to use is either AdSense Plugin WP QUADS or Ad Inserter.

Can anyone teach me how to edit theme codes to insert plugin tag? Thank you.