If I understand your first issue, you want to be able to run this code. You should be able to assign your macro to an action button (Insert > Shapes > Select an Action button down the bottom). Then when you run the presentation you should be able to click on the button and that will run your code. That's not the only way to do it but I believe that would be the simplest.
To confirm, this code should be placed on one of your modules (most likely called Module1) in the Visual Basic editor, as opposed to against a particular slide. That may be obvious but, since you're new to VBA, I thought it was worth making sure.
In case it's helpful, I've attached a simple Powerpoint Example of how to do the things you mentioned. I've tried to keep it as straightforward as possible. Keep in mind you will need to enable editing and enable macros to run this.
Please let me know if this isn't what you're looking for or if you have any questions.