I can't search in itunes, it only searches my library not the store

Did you click in the search box in the left sidebar?

Also see the following from Buy music from the iTunes Store - Apple Support

If you don't see the iTunes Store

In the latest version of macOS, the iTunes Store might be hidden. Here’s how to find it:

1. Open the Apple Music app.
2. In the menu bar, choose Music > Preferences.
3. Go to the General tab and select iTunes Store.
4. Click OK.

If you click in the search box at the top of the left sidebar, do any options show at the top right of the main window?