I can speak from experience on other powerconnect models,
first step is you need to plug a serial cable into it and run a 9600 terminal session up to it to set an ip address up. you assign the ip address to the vlan, same (well, similar.....) as a cisco
configure
interface vlan 1
ip address 1.1.1.2 255.255.255.0
exit
username admin password reallysecretpassword level 15
ip default-gateway 1.1.1.1
exit
that should get your gui up via http on 1.1.1.2
admin and reallysecretpassword should let you in.
(1.1.1.2 desired switch ip address, 1.1.1.1 network default gateway)