First of all, you have to know where you are. How to know where you are
Just look around.
Well, that's not enough of course :-). Suppose you're next to companies A and B. Search in Localizer for companies A and B and mark them, then open the information dialog for any of them and click on "Go!". You won't have difficulties in finding yourself between two marked places (in red). Open the "Search in marked items" dialog to unmark A and B now that you found yourself.
Once you know where you are, don't forget to "set your position" ().
How to know where you want to go
Search for the place you want to go in the search dialog. Once you find whatever you're looking for, click on "Go" in its information dialog and you'll see where you want to go.
Note that this also works for presentations, in order to see where they're being held (for cases where it's not in the same company's stand but in a conference room, or somewhere in an open space in a hall).
How to get there from here
Ok, you know where you are and you know where you want to go. But you may be wondering "How do I get there from here ?" No problem, just click on "Go to Your Position" in the "Move" menu and an arrow will show pointing you to the direction you should be heading to. At this point, you can take your PDA in your hand, put the map in "pan" mode and start walking moving the map as you pass through stands and corridors. The arrow will always point you to the right direction until you get there.
Note that the arrow may not be painted if you disabled it from the Options menu. in that case, you should do Zoom Out until you see both the place where you are (marked with the footsteps icon) and the place where you want to go (in red if you marked it), and trace a path by yourself (note: you don't want to really trace a line in your PDA display with a real pencil unless you're really interested in getting to that place and buy a new PDA ;-) ).
Note also that currently the arrow points in the direction where the place you want to go is, not the way you should go. This is not usually important as there're usually many corridors anywhere, but in the case that there's a wall separating you both, you'll have to go around the wall.