Your (undirected) network should be in edge-list format, listing one edge (as a tab-delimited pair of vertices) per line. You may specify a weight for each edge (as the third tab-delimited value), if no weight is given then the edge is assumed to be unweighted.
community must include the starting vertex
You may also download this application as a command-line executable here.
Boston University Computer Science Department & Bioinformatics Program