Java ferns have rhizomes that are not to be buried so substrate is not an issue.
You can tie them to rocks or DW via cotton string ... Eventually the roots will attach. Java ferns and Anubius plants are filter feeders ... Pulling nutrients from the water column ... So dosing liquid ferts is beneficial.
Both of these are low light, low maintenance plants that do not require CO2... Just dose ferts. You can find both of these at Petco's etc .... Good choice plants for beginners. Another option are crypts ... Another low light plant that can be buried in gravel, though sand is a bit better IMO. With crypts, there are a few different species to choose from ... Again available at Petco's.
The link below lists plants by their lighting requirements ... Check out low.
PlantGeek.net - Plant Guide