Ok, so you will have to upload steamcast and steamcast.conf (configuration file edited to suite your needs : passwords, logins, number of listeners, eventually the address of the current DNAS to relay, define if you need log files, name of the mount point (/stream.nsv for example)) Then CHMOD (with ...

What is your operating system please (this is to detail the instructions) ?

No, you will be able to feed one server at a time. BUT you will be able to relay the DNAS by Steamcast.