The starter on a 1998 Chrysler Concorde is located on the bottom of the engine, towards the passenger side (right side when sitting in the driver's seat). It's usually fairly close to the transmission bell housing.
However, precise access will depend on the engine (3.2L or 2.7L). You'll likely need to get underneath the car to see it clearly. A repair manual specific to your Concorde's engine will give the most accurate location and access instructions.
