Having your ideal customer profile in mind, use the filters within Prospector to generate a target list.
Option 1: Creating a target list for a Promote campaign
Once you have a list of accounts that you're happy with, make sure "company is targetable" is checked within the STATUS filter. This will reveal only companies which are able to be targeted within Promote campaigns.
Now your list has been created, it will be saved within Lists and available for you to select when creating a Promote campaign.
Option 2: Creating a target list that won't be used within a Promote campaign
Once you have a list of accounts that you're happy with, select Add to List and either add to an existing list or create a new list.