You can configure ads for the main page and for each project page separately. However if you do not configure ads for some project, main page ads will be displayed on this project page by default.
1. Default ads configuration
Main page ads are configured through the <portal-name>/ads directory in CMS. To place a new add, you just need an image of the right size.
When you have it ready, edit the <portal-name>/ads/ads.txt file. It is formatted according to this rule:
http://link1 , image_name1 ; http://link2, image_name2 ; (...) ; http://linkn, image_namen
Then, add the appropriate image to the <portal-name>/ads/images directory.
2. Project page ads configuration
To configure project specific ads, you need to edit appropriate project.xml file. For each ad you want to be displayed on the project pages, please append to the project.xml file the following:
<ad> <link>http://link1</link> <image>ads/images/image_name1</image> </ad>
and add the image to the <portal-name>/ads/images directory.