To move, press the W,A,S,D keys in the following way depending on the direction you wish to travel in :
W = Up
A = Left
S = Down
D = Right

Many people belieive that the W,A,S,D key functions are an easter egg included by Sir Edmund McMillen, this is false.
They are just difficult to find / get.

I hope this tutorial helped you learn to move on The Binding of Isaac : Rebirth.
Thanks for looking.