2. Go to Appearance > Editor
3. Choose your theme from the drop down on the right and click select
4. The first file that loads up most likely is your style.css file make sure the file is editable, either has a blue button that says Update File or has text that says "You need to make this file writable before you can save your changes. See the Codex for more information."
5. If you see the message that says you need to make this file writable, then follow the link to the Codex, and follow those directions. http://codex.wordpress.org/Changing_File_Permissions
6. If you see the blue button that reads "Update File" for style.css then place the following inside of that file, at the bottom.
Place in your themes style.css file
position: fixed; // makes sure it stays in place
top: 10px; left: 0; // places it 10px down and all the way right
z-index: 10; // make sure its on top of everything else
background: transparent; //
7. Great, now you need to find your header.php file and do the same but with the following code within the <head></head> tags:
Place in your header.php file
REMOVE THIS TEXT AND INSERT PAYPAL TEXT HERE
you might want to check out the following sites for more info on how everything works: