How to compile a server to use multiple processor cores?

[Althoe]

I've looked everywhere for C++ how to make a C++ program to use multiple cores of the CPU.

Anyone know where to find information about that?
Reason: When I backtrack an open tibia server what it uses, I can only see it uses 1 out of 7 cores....
And I want it to use all instead of one

Thanks for any answers!

 

[TKO]

You need to source edit alot for it!