XF 1.5 adding something to sidebar

Hi, Im trying to add a button with an external link to the sidebar, reading the threads I found that I can do this using the ad_sidebar_below_visitor_panel but I dont know how to create a box in the sidebar, because I wrote "test" and the text appear in the sidebar without any box or something like that...

Any help?

This is how is now:

and this is what I want: