Installing programs on the Mac

[Natalie]

Hi, I just downloaded Adium so I can instant message with the Mac but  
am not sure how to instal it.  I remember hearing somewhere that I  
needed to move things to the applications folder.  So, do I need to  
move the disc image or the dmg file.  If you could send any responses  
off list since I am no mail at the moment, it would be helpful.  Thanks.
Natalie