I am a beginner in developing, and I still don't have the necessary knowledge.
The name on the module will be "Banner by category"

I want to add banner in category page in the left sidebar. And to set manually in which category to show content.
I copy and modify files from HTML content module. Add some code in the view.tpl file in admin and controller file.
I add field Category in module admin. But when click not working, not showing categories to select them.
Can see in admin panel
http://oc.sieich.com/admin
user/pass
admin/admin
Extensions/Modules/HTML Content Pro -> Brand Banner Category
And another question is how to modify the code in the controller to work when the category is selected?
This is module code in GitHub I upload
https://github.com/chichebiev/BannerByCategory
I need from this functionality and I think the module will be helpful for another people and if I can do it a success. I will publish the module free. Please help me to create together the module.