Creating a custom block

Store Builder Questions
1

I want to create a completely new custom block. I’ve figured out we need to add a new tpl file in the addons folder and then this can be seen when adding the block to the page, but i want to populate it with tags. the problem here is the “filling” select is disabled :S

2

Where do I need to create this custom template??

I don’t need to edit the content.



thanks.