I am searching for a sites where I can showcase art.

The internet is awash with millions of fine and not so fine art.
3 sites in know of are DeviantArt, Etsy, and Ebay. I would start with the first one, although it seems to have changed over the years, and all I see are prints anyway.
It isn't easy to sell art online for other reasons - your photography must be excellent, your computer must be able to handle high resolution and color transmission well, and your viewers can never really 'see' the nuances and textures of paintings.
Then there's shipping, which is expensive, even if there is no glass to deal with.

How about showing us just one here?