You can use iSpring Online to sell your courses uploaded to your account. Before you enable E-Commerce for your course, you should configure your payment options to be able to accept payments online. For now, iSpring Online supports PayPal services only.
To link your PayPal account to your iSpring Online account:

If you change your currency here, iSpring Online WILL NOT convert existing prices for paid content, it will just change the currency. So make sure you change the prices as well.
Make sure you configured your Paypal Website Payments account to accept payments from your iSpring Online account.