How do I setup a bot to open trades while there are manual trades open in an existing account?

I want it to keep track of only the trades it takes and upon closing for profit, only close the trades it has taken.

Can anyone shed some light? I looked at the close symbol and magic number functions, but am not sure how to use them. All I need are a few examples. The mql4 documentation is so cryptic....

Thanks for any help.