Mightymike.
Pretty easy and it is a quality service. go to www.paypal.com and sign up for an account. You will need to attach either a credit card or some sort of a savings or checking account to your profile.
Once things are st up, which will take a few days because they will deposit a few dollar intro your account to ensure all is working, then you can send anyone money by just using their e-mail.
Or, you can ask the seller to send you an invoice. either way leads to the same end result, just a different path.
I have had my paypal account for nearly 10 years. Have spent and received near 9000 grand thru the system and never had a single issue to date...