Did the seller send you an invoice? Did eBay send you an invoice?
From either kind of invoice, you should be able to click on the PAY NOW button, and pay from your Paypal account.
Since you have a few feedback, you must have an account that you have used successfully.
If you have not received an invoice, ask for one in the Dispute's text box.
"I want to pay, but I do not have an invoice. Please send one." (I include this because English is not your first language and it is important to be clear and simple. Your seller may be in the same situation.)
