Unless you are connected with the upper-end art world there's no market for art right now.

On of my sisters is an artist who sells online. There's Etsy and eBay. Plus Michaels has a companion website to their store site where artists and crafters can sell online. I don't recall the name but there's a link to the site on Michaels homepage. You can even sell handcrafted items through Amazon.

You could try setting up an Etsy shop. Just snap pictures of your paintings using the camera on your smart phone or tablet and upload to your 'shop' there. See if your paintings attract any attention. If you're not signed up for using PayPal to get paid that's easy to do from the PayPal app.