Translation:Nej, hej då!
With all my respect to fellow learners, don't follow their suggestions, please. If you want to learn the language and namely to learn writing, all these Alt-123 tricks don't go. You should install a Swedish keyboard. In Windows, go to Regional and language settings (go to Start Menu and type "Region" in the Search box - works since Windows Vista). Then go to the "Keyboards and languages" tab. Click "Change keyboards" and then "Add". Search for Swedish (Sweden) and click "Apply" then "OK" appropriate number of times. You're done, and: Å is on the [ key, Ä is on the apostrophe, and Ö is on the semicolon, i.e. ; .
Windows: å = Alt + 134, Å = Alt + 143, ä = Alt + 132, Ä = Alt + 142, ö = Alt + 148, Ö = Alt + 153
Note: from my experience, alt codes only work when you use the number pad, not the top row of keys.
Mac: å = option + a, Å = option + shift + a, To umlaut a letter, option + u then type the letter that you wish to be "umlauted".
The number pad is used with the NUM LOCK on.
However, I highly recommend installing the International keyboard. http://support.microsoft.com/kb/306560 Scroll down for information on how to create the accents ( ' + a = á) (" + a = ä), but what they forgot to tell you is that if you hold the right ALT key and press W key, then you will get å.
In my little corner of Norrland the most common farewell is ''hej hej''. I think I may have heard it around the bigger cities but I'll have to pay more attention next time. As I expected, ''hej hej'' was not an acceptable answer here. I am not a native and wonder about your experiences with ''hej hej''