I have used the bases for my Orks and on my IG army (if you can call two squads of guys an army)
First step is to glue the sand down to the base. Once it has After that prime it black.
Next give it a coat of P3 Gun Corps Brown.
Wash it with P3 Bloodstone.
Wash it with P3 Umbral Umber.
Drybrush with Gun Corps Brown.
And then finish it off by drybrusing it with P3 Hammerfall Khaki.
Easy as that (actually a lot more work than I do for my grey bases but I like the way it looks.)