To leave feedback on eBay as a buyer, you can follow these steps:

1. Log in to your eBay account.
2. Go to My eBay.
3. Find the item you want to leave feedback for and select "Leave feedback".
4. Choose the appropriate rating and add comments about your transaction.
5. Click "Leave Feedback" to save and submit your feedback.

You can also leave a follow-up comment by going to Feedback left for others and selecting "Follow up" next to the item number.