Connect to PAYPAL.COM
Click on Merchant Services
Look on the bottom of the page, click on "Buy Now Buttons"
Choose the type of payment, Donation in this case
Choose also currenct and a name that helps identifyng the payment
Click "Create Button..."
A new window appears with the HTML that configures the payments, copy the blue code:
Go to you blogger blog, select Layout, Chanege HTML
Save a backup of your model.
Click on "Expand widget model", this is fundamental.
Look the HTML code and find the "data:post.body" TAG, insert after this tag your PAYPAL html code.
Blogger needs well formed HTML, all the inputs field need to end with "/>" the closing tag.
Correct the missing closing tags.
Click on preview....and .. .thats all, now you have a paypal footer in all your posts.
Don't forget to save the model!!!
Hope it helps!