I need help trying to figure out how to use constructors...

In one example we are supposed to do the following:

You are given  a class named  Clock that has one int instance variable  called hours . Write a constructor  for the class  Clock that takes one parameter , an int  , and gives its value  to hours.


I just can't figure out how to take a parameter and assign it to "hours"??

In another example we had to:

You are given  a class named  Clock that has one int instance variable  called hours . Write a constructor  with no parameters  for the class  Clock . The constructor  should set hours to 12 .

Now, I get this...

Clock ()
{
hours = 12;
}

That's simple enough, but I can't seem to take the leap from there to take a parameter and give its value to hours. Maybe this is just me overthinking the whole situation, but any tips or assistance would be greatly appreciated.

Thanks,
Susan