I am pretty good with PHP and am used to coding everything from simple websites to custom CMS systems. I am, however, unsure how to get the Paypal integration to work. What I've got is a custom Wordpress plugin that I've developed for a client. It is an ad module and I need to have to user pay for these ads with a monthly Paypal subscription.
So where I'm stuck is how to integrate with Paypal. I've found the SDK PHP download, I've found code samples, but no where can I find a step-by-step initial setup guide. I'm not sure how to install the API certificate, where to put the API username, password, etc... and I'm not sure where to place the SDK files to get started.
Any input would be greatly appreciated. I'm past deadline on this project and could use the help.