There are many runs at Monarch that are labeled black (most difficult = expert) that are really hard blues. If you want to ski your FIRST black run ever, try something short and friendly like Picante. You can find this from the Panorama Lift off the Great Divide Run.
Some other good choices for black runs are Kanonen and Tango. Both of these are steep but straightforward blacks, with easy bumps on the sides of the runs. Find both of these from the Garfield lift.
If you want to really ski a black run, challenge yourself with High Anxiety. It is a true expert run, long and steep with real moguls. If you can ski this well and in control, you can call yourself an expert skier.
(So steep that you can’t see it without leaning out and over the hill. Yup, it is tucked in there between the foreground and the flatter run at the bottom.)