Installing BlogThis!
There are two ways to use BlogThis!: if you use Windows and Internet Explorer, you can use BlogThis! straight from the Google Toolbar. You can install Google Toolbar by going to Google Toolbar.
If you're on another browser, just drag the link below to your browser's Link bar.
Help.Blogger.Com
Once you have BlogThis! installed, try clicking on the icon. You will get a small screen that looks like this:

The upper right hand corner has a listing of each one of your blogs. When you use BlogThis! correctly, all of the fields will be filled in automatically.