Python highlighter/new file menu item for certain file extension

Hello,

I want to use the (internal) Python highlighter for a certain file extension.
What must I do? And I want an entry in the new file menu list.

Many thanks and greetings
padFox

Go to highlighter settings, select Python
On the second tab add your extension to Python extension list

What must I do? And I want an entry in the new file menu list.

Open menu settings / highlighter settings and ensure there is checked checkbox before Python item in the list of highlighter.
You can remove highlighters you don't need from the menu new e.t.c.