Add to Cart button, OR ability to change Quantity

[Marion2318]

Hello, i've read some of the posts here for the Paypal Options but I'm having trouble understanding what I need to do...all I'm looking for is to be able to have a quantity on my membership products. I have S2Member Pro with Paypal Pro. Can someone advise me the best way to allow the purchaser to purchase one or more memberships at a time?

Thank you for any help you can give.