I got our chapter started on
www.geni.com. It's a pretty simple interface and the last time I updated the tree you could still import profiles from facebook, so everyone's info and picture were automatically filled in.
They also let you export the whole tree into a GEDCOM file so you can take it elsewhere in case they close down or start charging a bunch of money. So far we've got over 150 of our 1000+ brothers in the tree, so lots more work to go! It's a good thing you're starting while the chapter is young; it'll be a lot easier to keep track of.