How to Control My Own Ad Space on Blogspot

Manually
1. Determine how you want to sell your space. Going directly to advertisers gives you complete control over ad content, placement and duration. However, this involves setting your own prices and contacting potential advertisers directly. Third-party services that handle ad placement for you include Project Wonderful and adBrite. These services allow you to set up an publisher account that includes the kind of ad you have for sale; advertisers then bid on your ad space.
2. Set the size of your ad. If you're working directly with advertisers this is a much more flexible issue. If you're using an ad service check to see which ad sizes they support. Common Web banner sizes include the square (either 125 or 250 pixels square), the skyscraper (120x600 pixels) and the full banner (468x60 pixels).

3. Create your ad widget. Go to your Blogger dashboard and click the 'Design' link below your blog. Click the 'Add Gadget' link and select the 'HTML/Javascript' widget.
4. Enter a title if you want it above your ad space. You don't need one but having it there can allow you to indicate to visitors that this space is for an ad. In the content box add the HTML or Javascript for your ad. If you're selling ad space directly, this only really requires the ad provided to your by your advertiser and a link; an incredibly basic image ad with a link would look like this:


If you're using a service for your ad space the code for including your ad will be provided to you by said service; simply paste it in this content box. Click 'Save' when you're done.
5. Move the ad where you want it on your blog. By default Blogger adds the widget to the top of your sidebar but you can also place it after posts or drag it further down on the sidebar. Click the 'Save' button on the layout page to save the changes to your blog.
Using AdSense
6. Go to your Blogger dashboard and click the 'Monetize' link below your blog. On the monetize page click the 'Sign Up for AdSense' button.
7. Choose where you want ads to appear on your blog. Your options are to set them on both your sidebar and under your posts, just on your sidebar, just under your posts or none. Click 'Next.'
8. Sign up for AdSense with a new account if prompted; if you already have an account you will be asked if you want to use your existing account. Once set up, Blogger will give you the option to go your blog to view your ads or go to your layout page to change the placement of the ads.
9. Click the 'Monetize' tab to view your AdSense earnings or to set up AdSense within your feed.