Help with tab search and other things

Hello good afternoon

I’m trying to fix differents problems for several days ago…

¿How can I put the search tab to help people to find my blog content? I’ve putted but it doesn’t work

¿How can I link the ads plugin with my adsense account? I already have an adsense account

I am trying to put the Youtube icon on the footbar but is no working…

Thank u so much