"How Do I Add A Donate Button To My Blog?"
The most simplest (and best) way that I know of to add a donation button to your blog is for you to sign up with Paypal.
As you can see by looking at this blog there is a Paypal button on here.
You have to join the Paypal program first and you will need a bank account and a credit or debit card.
Once you have been accepted into the program you can click on the merchant link and get your coding for adding a donation button to your site.