I suggest getting sand for your cories. It is prefered because cories like to dig through the sand. When I was going to get cories for my 10g (never did because my betta is a you-know-what) I was going to take a section of the gravel out and have a little sand area in the corner for them to play in. There is a little area on the right side of your tank where you don't have decorations, you could put some there.
Oh also make sure to keep an eye on your water parameters because cories are sensitive and it is generally recommended to only introduce them into a cycled tank. If your tank is already cycled, then nevermind!