[C++] Memory reading help

[Justei]

Hello, i am kinda new to c++ and i need help, i have successfully injected a dll into a process, so, now i need help because i need to make a function that reads a value of a specified adress...

I don't rly know what function i should use to make it the most efficient, and also, i would love if you could explain HOW to use it in detail...