apt-get won't update

[MICHAEL WEAVER]

    After re-installing my who Ubuntu system on my laptop yesterday, I 
can't seem to do any apt commands for updating my system or installing 
Gnucash.
It keeps giving me messages to do with errors and resolving.
What I did was hook my broadband modem up to my laptop without using my 
wireless card and I thought it would switch to use my wired broadband.
Do I need to set anything in Edgy before I can upgrade my system or 
install packages using my wired Broadband connection?
I was actually told by someone who helped me last time before I messed 
up my system and had to re-install last night that I didn't necessarily 
need to use Network Manager but the problem is I don't know how it was done.