You'll want to check out the Mir 2 Advertisements section and download the client for one of the servers listed there. LOMCN's download links will be useful if you want to setup your own local server to play around with or testing, otherwise you'll likely want to play one of the many custom servers advertised here. You can see current user counts across all the servers using the Mir Tracks link at the top, then find the advert (in the aforementioned Mir 2 Advertisements section), have a read through and give one a try.