new MTB creacking on hard pedaling When I press down hard on my right foot trying to go fast or up a hill I hear a noise coming from my bike. What is this? Its brand new... If it isn't an easy fix I will take it back. It only happens with my right foot and when pressing down hard...

Oh also on my wife now bike if you press too hard on each pedal there is a creaking noise. What is this? sounds something is not lubed. It is a new bike also.

Thanks in advance.
If only one side is creaking, it's probably the pedal or crank arm not screwed tight. So first tight them up (for the pedal you probably need a special wrench, for crank arm it's a 8mm hex or 14mm wrench). You should tight it as fast as you can, as it can brake the crank arm.  

When both sides are creaking, it could be that both sides are loose, but it also can be a problem in wheels i.e. spokes are loose, or hub is broken, or it can be the BB.  

Those are the much common problems, but as @mattM linked at sheldon brown, it can be other things as well.