Advertising Setup

I have not joined AdSense and hope to sell my own ads. I am in the process of setting up a sample site to show prospective advertisers before creating the live site (importing from another older format). This looks awesome for using AdSense, but can I set this up to manage my own ads and assign positions and so on? I cannot find where to do that. When I created a sidebar ad (for example) it placed that one sidebar ad 3 times on the imported theme page. I, of course, want to show a multiple of different ads and even create some other ads sizes. Do you have a tutorial to teach this? Or?

Thank you in advance

Thank you for your reply Bogdan, but your link does nothing to address my question about assigning different ads to different positions and pages if I want to administer the advertising myself. I do not plan on using AdSense, but want to sell my own ads within my own industry. This theme does not allow me to that? Or should I use a plug-in advertising manager? I see a couple on the Envato market.

Thank you