Domain forwarding fail

I went in to GoDaddy set our Pack domain to be forwarded to the trooptrack site but when I did that the trooptrack site would not display correctly. It looked like it had no styling?! I backed out the changes and then things started appearing normally again.

So how does one forward an existing domain?

If not possible, what are my options here to keep the previous domain working but somehow direct users to trooptrack?

Thanks in advance