Need help installing .deb package

[Siri Amrit Kaur]

I just downloaded the Opera .deb to my /home/[user] partition. How do 
I install it? What directory do I install it to? What are the 
commands and do I need to be root? I want it installed so all users 
can use it. 

I've used apt-get install to download and install packages before, but 
for a package that's already been downloaded, I don't know what to do 
with it. 

Thanks,
Siri Amrit