There are a few methods to do this, the C++ tutorials go over how to spawn something utilizing a spawning volume. Basically you create a blueprint with a large square volume and choose a random point from within that volume. However the other method which sounds more like what you want is to use the [level blueprint][1] and the BeginPlay event. You want to generate a [random number between][2] 0 and 1 to choose which point to spawn the the actor at. Then you [spawn the actor][3]
ActorOrPawnClass * actorOrPawn = SpawnActor<AYourActorOrPawnClass>(TargetLocation, TargetRotation, NULL, NULL, true);
or in blueprints
If you have not done so already I highly recommend looking through the tutorials on blueprints, they will take you about a day and should help immensely.
[Introduction to Blueprints][5]
[Blueprint Essentials][6]
[C++ Programming][7]
Hope this helps
