lol no secret here, I'm a newbie at this too, Marissa. I went to pages and pages and see familiar instruction. Here's how to do it.
-Drainage layer: gravel, hydroton, rock, whatever that doesn't break down.
-Charcoal layer to absorb chemicals
-A layer of moss or something similar to separate the soil from the drainage layer (I use paper towel, lol not sure if it works, so far I have no problem.)
-Soil of course....., for the paph, I use coconut husk mix with peat moss.
-Top layer is for decorative purpose. I use moss because I can find them outside everywhere at so I just dig a little.
Again, no secret here, lol I've just finished that terratium for a week or so, therefore I don't want to say that it works fine there, but so far so good.
You can add leaf litter or rocks so it looks more natural.