Go to Appearance > Widgets to add your advertisement code in a text widget using the sidebar called "Single Right Advertisement". Shortcodes are allowed in this section.
Yeah I use to hit up your site all the time back in the day. Then I stopped and forgot about it (no offense) because you di1#8n&2d7;t do to much with it for a few years. Then today I visited your domain and was like whoa is this the same dude. I read your about page and yup. So I don’t know what the point of this was but whatever. Have fun.