Awhile back I did this DIY on another Fit forum, so, I thought I would share here as well.

Open Glove Box:



Pull in the left and right side of the glove box like so. This will allow the compartment to open up fully.



Anything inside will fall out on the floor.



On both side pinch in these tabs that hold the filter in. While doing so pull it towards you. This is where the filter element is.



Filter in tray:



Take out the filter and replace with the new one. It should only go in one way as there is a direction for the air flow marked on the plastic tray.

Take note that the ECU is in that location as well. Just an FYI.