Mike,
In Arcmap with your layer added. Click the Editor menu on the Editor toolbar and click Start Editing.
Open the Create Features window by clicking Create Features on the Editor toolbar.
In the Create Features window, click your manhole point feature template. This sets up the editing environment so that you will be creating new point features in the manhole layer.
Right click on the map and select absolute x y (I think F6 also takes you here). Type in your coords to create a new feature
Regards
Anthony