How to create custom template ?

[becafuel]

Hi all !

I'm trying to create a new navigation bar, based on the existing one, but with fewer infos inside, so I can put it at the end of the subjects list in thread view.

So, I've created a "new template", assigned it a name : "mybar", and simply copied the content of the existing "navbar" code inside, to test that it can work.

Sadly enough, it doesn't work I've added $mybar in the SHOWTHREAD default template where I want it to appear but nothing appears. If I add $navbar or a string like "my stuff" then it works, but if I use $mybar it doesn't.
I think something is missing somewhere, as I can see this

Please note: When adding custom templates, in order to have them parsed, you must also write PHP code to call them.

in the help of the "new template name".

So my question is : how or where should I put this php code ? or what am I doing wrong ?

I have successfully made other modifications, like adding a "go top" bar under member icon (in messages list), but it seems that all my "custom" stuff is not seen or isn't used

Thanks in advance for any tip.