Manual control step-by-step motor (no replies)

Hello,

I'm French and I have a small problem. I want controller manually two step-by-step motors (NEMA 17 I think), and I have only one Arduino Mega card and one RAMPS 1.4 shield (with four step-by-step motor controler).
I haven't temperature sensor or endstop.

I only want manually control my step-by-step motors for try my home-made structure, I don't want print any part.

Can you help me, it's very important.

Thanks guys.