creating subdomain

i want to create a subdomain on for my site. the problem is that i have no idea how. I have Ensim control panel running on my server (reseller account) but there's no option, since it's an old version of Ensim.

my friend tells me that i can create a subdomain from Telnet or something. I've been doing some research when I search for google with subdomain and telnet in it - only host offers come up.

in my remote login it says:

telnet
development
OpenSSH secure shell

would those help? i really want to create a subdomain. help!

thanks in advance...

-Nay