How can I receive an invoice that I can pay directly?

I would like to receive an invoice for payment (the user sends me their bill so I can pay them online) after services rendered. 

What is the best way to receive this invoice and pay them  through paypal or other payment method online? Thanks.

Not sure what you meant, are your clients or users paying you? Or is it the other way around?

If you want to ask payments from your users, you can setup an order form, you can integrate payment processors that we support (like Paypal, Authorize.net, etc...). 

You can check this guide on how to setup an order form: http://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form. To learn more about our Payment integration, please check this guide: http://www.jotform.com/help/323-Mastering-Payment-Form-Integrations-with-JotForm.

If you want to receive payments by your authorization, you can do that by following this guide: http://www.jotform.com/help/292-How-to-Enable-Payment-Authorization.

Do let us know if this helps.

Thanks but I need to pay for services. Can a person send me a bill by a form, after he uploads the form for services. 

This will be the reverse. I receive the form, I click on it. And it goes to paypal so I can pay him.

Unfortunately, I'm not sure if that's possible in your end. They could register an account to JotForm, create their own form then send it to you. They also need to have a Merchant account in Paypal to sell services, they can provide you an invoice from there.

Or, they can setup an order form and use the "Purchase Order" under the Payment tools if they want their users to pay in another method.

I believe this setup that you are looking for is much more related to the merchant side, they are the ones who can setup the order form, choose a payment method that they prefer and give you the invoices. In this case, from what I understand, you are more of the customer.