Originating from America, the Hydrocotyle verticillata with its toadstool like leaves, is a fairly simple plant to care for. In terms of size the more light intensity you have the smaller and more compact this plant will become. It isn't very fussy about CO2 or fertilisation, although good CO2 and nutrients will improve growth.
When first planting, separate the runners to include one leaf, plant into the substrate and watch it spread. Prune by cutting unwanted runners with sharp scissors.