Hi,
this isn't too hard if you're already on the network.
Edit the following:
/etc/resolv.conf
and put in info like
nameserver 1.2.3.4
nameserver 5.6.7.8
(where 1.2.3.4 is your primary DNS server and 5.6.7.8 is your secondary DNS)
/etc/defaultrouter
edit this file - just put in the IP address of your default gateway.
Also, you need to edit your nsswitch.conf and put dns after files for hosts. If you are not using any name services or anything already on this machine you can simply do
cd /etc
cp nsswitch.dns nsswitch.conf
Now you can just restart inet services with
/etc/init.d/inetsvc stop
/etc/init.d/inetsvc start
You'll have to set up the appropriate info in Netscape obviously if you're using a proxy and so on.
Personally I find Netscape is slow and bulky at the best of times. You can get a Solaris Opera beta which is very fast and much better IMO.