Setting up paypal with your website

Hi everyone,

I have made my first product for IM, it is a PDF. Out of all the videos I have watched not one has showed me how to do this. Probably because it should be self explanatory. I am using wordpress btw.

When someone pays me money via paypal for a downloadable file, how do I automatically respond with the download link?!!

This should be easy for you guys to answer I hope .

I am using Aweber and have found a tutorial about setting up a aweber email with paypal and then going to the merchant tab in paypal to creat a "buy it now" button. However, frustratingly the last step of the tutorial tells me to select a button in paypal "add more options" it is the last part of the tutorial and it does not match up with the paypal page I am staring at!

For those that do it this way, do I have to upgrade paypal to see this option?

I have contacted Aweber about it have heard nothing yet.

I have also tried using the Wp e-commerce plugin, this was my B plan for selling my product...This time I have uploaded the PDF file within the plugin and thought I set up everything correctly. I got a friend to buy the report off of me...
Its great I receive my money but they never received any information about how to get the PDF they paid for! Good customer service .

I am no doubt being silly and missing something really easy. But if you guys could please point out how you do it so well I would be very grateful.

Thanks!

Andy