getting started profiling c++ with shark on OSx

[Lola]

Hi, I would be very happy if someone could help me with the following:

I am trying to optimize a c++ code on a Mac OSx 10.5.8 using shark 4.7.0.
Now I do not know:

-Can I just run my program in the terminal and start Shark? or do I have to compile it some special way using xcode?

-do I have to split my program into functions in order to get useful information?
Or is there a way I do not have to write everything into functions? At the moment my program is very short so I did not use any functions.

-how does the data mining work? I know it is a way to focus on the data i am interested in but I do not understand what "charge symbol ... to callers" or "flatten library ..." means.

If someone can give me some hints, knows a detailed tutorial I would be very happy, I feel I am a bit lost. It is just too much I do not understand and know about.

Tanks a lot! Lola