To run a fan night in MyGM, go to the business section of the mode and open up sponsorships. Scroll through the list of sponsors to find any that you have a good relationship with. Then, go into the sponsorship agreement and click on "Run Fan Night" under the relevant category. On the next screen, you will need to input all of the details for your fan night, such as date, time, and location. You can also choose to promote specific players or teams during your fan night event. Finally, you will need to pay your sponsorship fee and select which players and teams are eligible to participate in your event.