Your hatchling needs a substrate that can hold humidity. You can buy cypress mulch at the pet store or something like the 'Forest floor bark'. The Tortoise Trust (check out their excellent website at www.tortoisetrust.org,- you will find many useful articles on nutrition and husbandry of humid habitat tortoises) also recommends a mix of about 2 parts loam and 1 part playpit and, but I find this too messy.
I personally use an about 2 inch layer of forest floor bark (petstore) with 1 to 2 inches high of spaghnum moss (garden center, holds water like a sponge), which I moisten with a spraybottle twice a day. The half flower pot hide houses are all filled with the spaghnum and the babies dig into it. Most of the day they spend with their back in the moss and the front looking out to see, what's going on. That way they stay well hydrated.
Of course a very shallow (~ 5 mm deep) bath dish should be provided at all times and I give a longer bath to my hatchlings every second day before they are fed.
To feed them I put them in a plastic dish pan with a big plate of food and let them eat for about an hour (in an appropriately warm place). They always seem to poop into the bath at this time or while eating in the plastic pan (which is easy to clean and helps to prevend, that they ingest any substrate), so the substrate in the enclosure does not have to be changed frequently.
To make sure, that there are no bugs / eggs in the substrates I moisten them, place them into a big single use aluminum pan, cover it with aluminum foil with some holes punched in and bake the whole thing at 350 degrees F for an hour. Worth the effort, because I have never had any little bugs, mites or any mold growing in it, even after months.
It is very, very important, that your hatchling is able to bury himself (check out the article on 'microclimates' in the Tortoise Trust article section, it will help you to understand your babies needs a lot)!
Good luck, Gaby