You need to invite people for the evaluation phase of your program. This is done from Evaluation > Judges. Press Add judge to invite a new judge.
The people you invite will receive an email notifying them of the invitation, along with their login details and a link to the evaluation portal.
You can assign a judge to one or more of the application categories you've created in Settings > Categories. Leaving this blank means this judge can evaluate all applications from every category.
You can assign a judge to one or more of the program's evaluation rounds, as set in Evaluation > Rounds. Leaving this blank means this judge can evaluate applications across all evaluation rounds.