SMF Forum
Logo - Go to your SMF Admin...Configuration...Current Theme. Scroll down to "Theme Options and Preferences"...Logo image URL. Replace with the logo you wish. Make sure it will fit properly in the space allowed for the theme you are using.
Banners in posts linked - To link banners within forum posts use the following code. Replace the sizes with the size of your banner if necessary.
[url=http://www.link-url][img width=468 height=60]http://www.your-site-url/your-image-folder/image-name[/img][/url]
Here's a completed example: [url=http://www.fiercewebsites.com/recommends/web-ceo.php][img width=468 height=60]http://www.fiercewebsites.com/images/web-ceo_468x60.gif[/img][/url]
Banner or ad at top and/or bottom of SMF Forum - You can easily add either using the Global Headers and Footers modification.
When you install Global Headers and Footers mod, it will give you an easy access link in Admin under "Configuration". It is very easy to use and change as you like. Banners will appear on all pages of your forum.
Banner or ad in your choice of positions - SimpleAds is an easy to use Mod that gives you the option of putting your ad in many different positions on your forum. It installs easily to a forum using 2.0 RC3. SimpleAds does seem to cause an avatar loading error problem, but it can be easily fixed by following the directions in this thread.