to talk to paypal you need to know the mechanism (usually called an API) to send and request information form PayPal.. that shold be available form Paypal.
MySQL is a competant db sever engine.. there are lots of db candidates out there.. but MySQL is as good as any. For what you want I wouldn't rule out MS Access, Filemaker or Paradox.
you need some knowledge of an interface language (whether you do that within Access, use a server side scripting language such as PHP, ASP, or a plain old style development environment such as VB, VC++, C#, Delphi..... so that your db can talk to PayPal.
But as you say you are "clueless" Im not sure this is the right forum for you, it sounds like tyou need helkp with the basics of design, coding, and interfacing to external systems.... all of which are beyond the scope of this site.. we will try to help, but this site isn't about teaching, it isn't about doing work for people, its about helping people with db related developemnt issues as a community.
It may be worthwhile having a look at sites such as W3schools.
Id suggest you so some basic research & fact discovery on what it is you want, what you need to do to interface to Paypal, and then decide what you cant reasonably do given your current experience, knowledge and competence. There's no harm in trying, it may eve be a good 'project' to learn on.. just this isn't a teaching or training resource.
There are lots of people here who may help, and provide pointers or answers to perplexing questions, but they cannot, and almost certainly will not take you through the whole process or do it for you. If you try to go down that route, you will exhaust even the most charitable respondent here's patience, long before you complete the first screen.
I'd rather be riding on the Tiger 800 or the Norton