http://www.youtube.com/watch?v=mpQEIR1AZLY
Start from 14:30.
The guy says to type tool bitmaps levels\beginner\bitmaps.
If you watch the whole video you understand. The "beginner" thing is just the name of his map. We just name it the name of the map we want. I did the gmax stuff but I am stuck on tool.

did you get a error saying warning, meaning the bitmap/bitmaps were not created?
if so just open guerilla click file/open then go to your maps folder and open your bitmaps folder
select your bitmap and open it then in the guerilla window click on the drop down box called format and change this to compressed with explicit alpha, click close on guerilla and in the option window click yes to save it. now back on your cmd/tool window just press the up key on your keyboard (this brings up the last command you entered) press enter and that's it it should say created.

no my problem is that tool says 'tool' is not recognized as an internal or external command, operable program or batch file