After struggling myself, and wading through several threads to glean the crucial pieces, I have come up with the following. It is intended as a gift to this community, to make the donate button truly easy for folks.
I would love people to test it, please. Anything missing? Extraneous? Confusing?
NOTE: After posting, I see that I cannot make the "href..." part appear. Can a moderator fix that (or tell me how to), please?
1. Print this page so you can follow the steps easily.
2. Login in to your PayPal account.
3. On the tab bar, choose "Merchant Tools".
4. In the left sidebar, choose "Website Payment Standards".
5. Under "Website Payment Standards" choose "Feature List".
6. Scroll down. Under "Payment Processing Options" find "Donations".
7. Click "set it up".
8. In the "Donation Name/Service" field (blank bar), enter a name for the project.
9. In the "Donation ID/Number" field, you can enter any number or leave it blank.
10. In the "Donation Amount" field, leaving it blank lets the donor decide how much to give.
11. Choose a currency and country. (Probably that which you expect to receive most donations in and from, but you can choose any you like.)
12. Scroll down to "Security Settings".
13. Choose "no" (...as to whether to encrypt. Your email address will display to the donor, but the transaction will be secure.)
14. Click "Create Button Now".
15. Ignore the "HTML Code for Websites" box. I said ignore it.
16. In the "Link for Emails" box, there is another code. Copy it.
17. In the gibbledeegook below, use the code you just copied to replace the words "insert website link here". Leave the quotation marks in.*
18. Copy the whole code you just edited.
19. Go to the webpage you want your button in. In the "Visual" editor, place your cursor where you want your donate button to go.
20. Click the "Code" option for the editor. Paste your code in.
21. Go back to the "visual" editor. You should see a tidy "donate" button.
22. Click it to test.
*If you want to put a different donation image in, use the link below. Put the image code where it currently says "insert picture file link here including file extension.gif". Keep the quotation marks in.