What exactly are you trying to do? I need a little more to go on. Are you trying to edit someone elses map or make your own? In any case I have several links posted on another thread, and as this is the fourth time I have tried to respond to your thread (I keep hitting the wrong button and such when I try to copy the links) I will just give you the site for that page:
a pk3 is just the file that contains the map. You can open it either with software on your computer if you have it, or with a program that is called WinZip or a program that is called WinRAR (go to Google to find them). As for adding objects to a map, right click in the 2D window and a console will come down with all of the objects you need.
As far as that goes, there is not anyway (other than asking the owner for it). Technically, I think BSP-GUI contains a BSP to Map program that does it, but I am not entirely sure that it is legall to do, so I wouldn't do it. Your best bet would be to ask the owner to send it to you. Asking is the best way to avoid lawsuits.
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