How do you find out if you need a permit for a crane near a local airport in Seymore Indiana?

The relevant regulation is 14 CFR § 77.9. In relevant part, you need to inform the FAA and get permission if either is true:

The crane, or what you are constructing with it, will be taller than 200 feet above the ground level at the site.
The site is within 20000 feet of a runway, if the crane or the construction will pierce an imaginary 100 to 1 slope from the runway. So if it is 10000 feet away and more than 100 feet above the runway elevation, for example.

There are a few other rules as well, involving navigational aids and instrument approach procedures. Figuring this out is an very involved process. Fortunately the FAA has a tool where you can enter the latitude and longitude of your site and it will figure it out for you.

If you are required to notify the FAA, you must do it 45 days before you plan to erect the crane, and wait for the FAA to inform you that it has been determined to be no hazard to air navigation.

obstruction map around KSER, source: FAA

In the case of KSER, the map looks something like this.

The grey areas (about 4 miles in radius) are the areas around the runways that I mentioned above, and the rectangular areas are extra protection for approaches to the runways.