Firefox Explorer Help -

Someone posted the answer awhile back but I can't find it.
Got a new computer (Dell) and downloaded Firefox. Opens up and says it can't connect to the internet and it is a firewall or proxy issue. Went into the firewall program and added Mozilla to my safe list.
Ideas?
What makes this ironic is I am attempting to download the Microsoft Office program I just purchased. Sent an email to Microsoft and one of their suggestions was to use a different browser.
Got a new computer (Dell) and downloaded Firefox. Opens up and says it can't connect to the internet and it is a firewall or proxy issue. Went into the firewall program and added Mozilla to my safe list.
Ideas?
What makes this ironic is I am attempting to download the Microsoft Office program I just purchased. Sent an email to Microsoft and one of their suggestions was to use a different browser.