You can use the "Suitable For Events" designation in the Amenities section if you want to target the small portion of event planners searching for properties on Airbnb.
However, as an event manager, I don't find Airbnb to be suitable for the needs of those hosting event spaces. I'd recommend that you instead create a separate listing on a local site dedicated to event rentals, and work with someone who is aware of your city's laws, regulations, and insurance options. This is generally a much higher-risk use of your space than holiday rentals, and Airbnb is not equipped to deal with that.