command targe child question , help needed!!

[msarasa at fh-konstanz dot de]

I think this is the right command I have to use in order to connect gdb with 
an external proccess. As said in the help.
But , this is my case: 
I've made a simulator of a whole board with it's processor. I can run it as a 
process , and I want to know a little bit more about how to connect that with 
gdb. In the documentation there's no more said about how does target child 
work , and I would like to know, if it's possible , the way this command 
works. 
The format of the packets in this communication, the way I have to use it, and 
how exactly should I modify a program that reads from a simulated UART, to 
take the outputs from the gnu.
It's REALLY important for me a little help with this. If I should explain more 
about the simulator or the problem , please tell me!! but answer me anyway!!

I'm totally stopped at this point.
Thank you very much, 
Miguel.