If you are using the Content.ad plugin for WordPress, the Exit Pop and Mobile Slideup will have pre-selected placement. All you need to do is activate the widget and the unit will appear properly.
If you are manually installing the widget onto your site, you will need to copy the installation code from the "Widgets" tab in your Content.ad account and paste it directly on the page. You can also paste the installation code into a "Custom HTML" widget in WordPress and place that in the sidebar region. You will need to save it as an HTML.
By default, these units only appear once per session for each user.