Sure helps to know what kind of ped.
Assuming the pedals and cranks look like the average old european bicycle, the spindle through the frame is the pedal crank spindle, or crank spindle. The pedal cranks or cranks are attached to the crank spindle with cotter pins. The pedals are attached to the cranks by screwing them in, one is a left hand and the other a right hand thread.
Think about that a while then re-post your problem.