PayPal is a very popular system for accepting online payments, and is perfect if you want to easily sell products from your website. It lets you accept payment from other PayPal accounts, and from credit cards. It has fees, but they're far better than most other credit card processors.
If you want to accept payments online, having a PayPal payment option on your website is almost essential, as many people will only want to pay by PayPal.
You can transfer your PayPal balance to your bank account at any time.
You'll need to upload your products somewhere, and then set the page where the file is hosted as the "thankyou page" that the customer will be taken to after their PayPal purchase.
Sign up with somewhere like MediaFire
Upload your files there, but set the files to Private. Each file should have a page where you can download that file.
Back on the PayPal website, click on Step 3, then tick Take customers to this URL when they finish checkout, and put in the address of the page at MediaFire where your product is.
That's it. Now people can buy things from your website. You'll receive an email whenever someone makes a purchase. Then you can send the item the visitor has bought.