Step by Step Guide:
1. Login your Google Adsense account.
2. Go to setup tab.
3. Select a Product. ( Adsense For Contents, Adsense For Search or Adsense For Referals ).
4. Choose the Format/appearance of the Ads.
5. Click "Add Channels".
6. A pop-up window will appear. There you an fill in the "Name" of the Channels.
** Any name will do, use a name which can help you to Recognise the Ads you are tracking.
Eg: If you are having a site talking about Adsense and you are going to create Channels to track the Ads, then you can simply use name for the Channels like "My Adsense Site Ads" ( Only an example, you can use any name you like ).
** The main purpose of Naming the Channels are to help or make it easier for you to identify which Ads you are tracking.
7. Continue to generate the Ads Code. The Code of Channel will be added to the Ads Code generated. It will help you track the performance of the Ads.
8. Just Copy the Code and Paste to your site HTML and DONE. The Channel will help you track and the details will be shown in you Reports.