1. Log into Wordpress and navigate to the 'Thesis' control panel. Click on the 'Custom File Editor' to begin placing your new code.
2. Highlight the 'custom_functions.php' file from the drop down menu and click 'Edit.' Insert the following code into your header area once the file has opened.function thesis_header_ad() {?>
3. Replace where it says 'URL address' with the web address you'd like the ad to direct visitors to. Replace where it says 'image file URL address' with the web address of the image if the ad has one available. These settings will depend on the ad type you've selected through places such as Google. Some are text with images, text only or image only. Check for the appropriate code when building your ad through programs such as Google's Adsense.
4. Click the 'Save' button once you've finished and return to the 'Custom File Editor.' Open the file called 'custom.css' to show 'Thesis' where to place the ad in your header.
5. Copy the following code and paste it at the top of your 'custom.css' file..custom #header #banner_ad {float:right;margin-top:-7.5em;width:450px;padding-left: 1em;}
6. Edit the specifics such as 'float:right;' to 'float:left;' if you'd rather have the ad showing on the left-hand side of your header. Change where it says 'margin-top:-7.5em;' to whatever increment you feel is best. Play around with the numbers until you get the ad placement the way you like. Change the 'width' if the image for your ad is larger or smaller than '450px.'
7. Click on the big 'Save' button once you've finished and check your site for any errors. Go back and make changes to the 'custom_functions.php' and 'custom.css' files should they need them.