Drag (just use the Move Tool - hit the letter V) the image/texture onto the 3D render, hit Ctrl+T for the Transform Tool, size it down to the general proportions, then Right-click and choose Distort.

Click and drag each of the corners roughly to the shape of the face of the object you want it on - I'm making this the big front face of the block.

It doesn't have to be EXACT - I usually make a mask and paint black what I don't want to be seen - namely the portions that go "outside the lines."