In order to see the details for your prospects and begin contacting them or exporting them, you'll need to make an Active Prospect List. You can only have one Active Prospect List at any given time, so make sure you're happy with your list before you decide to make it active.
There are a couple different ways to make a list "active." Here's a page-by-page breakdown of how to do it.
On the ICPs and Prospect Lists page: scroll through the list of ICPs until you find the one you're looking for. Then click "Prospect Lists." Scroll through your prospect lists connected to that ICP until you find the one you want to work with. Next click "Make Active."
On the Filter and Rank page: if you've been working on filtering and/or ranking a prospect list then decide it's the right one to make active, just click to the Save tab. You'll see a space to edit the name and description of the prospect list as well as a button that says "Save and Make Active."
On the Active Prospect List page: this page shows you your Active Prospect List but will also allow you to change which one is active.