Congrats on making the move to more advanced repairs, it's very rewarding.
Front brake rubbing can be one of a few things. To start, make sure the front hub is always mounted into the fork dropouts consistently in the same spot, and the the skewer is also properly tensioned (should take about 10-12 lbs. force to open the skewer when closed).
If the noise is a constant grinding when the wheel turns through a full revolution then the brake pads in the caliper are rubbing on the rotor. Either the pistons in the caliper need to be reseated, or the caliper needs to be repositioned relative to the fork.
If the noise is a short rub that occurs regularly during each revolution of the wheel then the rotor is bent. This requires some finesse to straighten the rotor and based on your experience I suggest you leave this to the local bike shop to avoid making the problem worse.
Here is a tutorial
that covers another model of disc brakes, but many of the concepts are the same for your Juicy 5's.