http://www.adsensedecorator.com/adsense-wordpress-sidebar-widget/
How can I display Adsense ads in my WordPress blog?
I tried adding a Text Widget to the sidebar and pasting the code, but it won’t work.
Step 1: Get a wordpress dot org blog and buy hosting on a site like godaddy
Step 2: Download the Google Adsense Plugin from Smullin Design (google it). The plugin author gives one on one help if you have any issues.
Step 3: If that doesnt work, go straight to google adsense and walk through the process.
If you want some alternatives to adsense, check out my blog (One of my most recent posts is “Adsense is NOT Cutting It!”
Google Adsense for WordPress Sidebar (Widget/Plugin)