You need to be able to keep the substrate damp, and with that sand as a substrate you won't be able to do that. Plus with straight sand there's always a worry of impaction. In my opinion you need to change that substrate. Use bed a beast/ sand a 50/50 mix; or fine grade orchid bark . It's important to have a moist substrate...
You should, as Maggie said, change your substrate. A 50/50 bed a beast/sand mix would be good. As for your hide, use a drill and drill a hole in the top of the container. Get yourself a thin bolt and stick it through the hole. Slide a sponge onto the bolt and screw on a nut to keep it on the bolt. You will then be able to just wet the sponge to help keep moisture. Then you can replace the sponge whenever you need to. Good Luck!
I of course agree with both Maggie and Dee a mixture of 50/50 bed a beast/sand mix or sand topsoil mixture is needed. And Dee's suggestion of how to afix your sponge is a great one. that way you can change out the sponge when needed. You can also hot glue a sponge to the top of the hide. or fill the hide with sphargum(sp?) moss and just dampen it. I find my hatchlings prefer the sponge in the hide to the sphargum moss. But a change in substrate is a Must to keep humidity up.
oh its not sand im not sure what it is cuz i got it so long ago (ill try to find out) but it is really like dirt...kinda looks like sand in that pic, it was really bright in there at the time.