C++ :: How To Create CPP File That Will Handle Random Number Generators

How to create .cpp file (new class) that will handle all the random number generators (<random> library) that main could possibly access. When I looked for a way how to implement random generators the examples were always in the main function or in a class in the main.cpp (with no header file and the generator was not seeded as I imagine it should be = only once in a program).

Questions follows after this malfunction code.

main.cpp
#include "randomizer.h"
int main() {
Randomizer randObject(0, 10, 125); //Set bounds and seed generator
int mainVar = randObject.getRandInt(); //Store newly generated random number for future work

[Code] .....

1) So I think that I should somehow declare these generators and distribution in the header file. Is it like declaring int a;?

I tried writing std::default_random_engine defGen; into the header file which only silenced compiler's errors but defGen wasn't seeded.

I have seen some examples using auto a = randInt(defGen); (or maybe with the use of auto a = std::bind.... But what does auto represent? I can't use it in the header file.

2) Can I ensure that the randObject is seeded only once? If for examle I need randObject2 with different boundMax, can I still use the same defGen which was seeded the first time? That should ensure better "randomness" through the program, shouldn't it?

3) Is there better way (and easy too) to "interface" random number generators? The class in the end should provide "get" function to acces int, double, bool, signed/unsigned... or some other specialities like random prime numbers, etc.

If it is anyhow related I am using Code::Blocks IDE with GCC compiler (4.7.1)