After you highlight the text, press Command+C to copy it to the "Clipboard," and then you're going to have to paste it from there into a text editor or word processor. TextEdit is one text editor included standard with OS X (the operating system your new iMac is running). Go to the Magnifying Glass icon at the upper-left hand corner of the screen, click on it, then type "textedit" in the blank that will appear. Click on the Top Hit, as I'm demonstrating below:
That should put you in the TextEdit Application Press Command+V to paste the text you copied to your Clipboard above.
Now Press Command+P and you'll get the standard OS X print dialog box, which will allow you to select the printer you wish to print to, how many copies you want to print, etc.