Firstly, assuming you have acrylic tank (didn't bother to look at first post again) then drill small hoole through tank wall near where fan will hang. Run wire from fan through the wall. Reconnect the fan to the power supply. I used this fan
Coralife 3-1/8" Cooling Fan Kit so you can safely mount fan totally inside your tank with no shock worries. I would seriously consider eliminating most outside air from tank except from manually controlled ports. That way you can keep high humidities. Like I said earlier I can easily maintain 90+ humidity for 24 hours with 5-second mistings every 4 hours (I've been able to move from 3 hour intervals to 4 hour intervals with this new tank). I'm thinking of going to 5 hour intervals.