Drupal 7 Members Directory Problem
You do not have any exposed filters. Under "Filter criteria" you need to define a filter which is exposed to the user. The block will then show up

EDIT
You already set the exposed filters to be shown in a block in your views administration on the right side. Now you find a block with the exposed filters in your block administration page. Here you can set the visibility of the block - maybe just show the block under the path of this view.