Hi Prabu,
With regards to searching for groups, that's currently not available in our API. I've forwarded a feature request to our developers, though I can't promise when or if it might be implemented.
For joining/leaving groups, you should be able to do so with group.join and group.leave. These do require a group_id, of course, so for now they're only useful for your app if you get a group ID by some means other than search.
Thanks,
Greg
