On a 1990 Ford Ranger with an A4LD transmission, the neutral safety switch is typically located
on the top of the transmission itself. It's a small switch, often with a single or a couple of wires connected to it. You'll likely need to look closely and possibly use a flashlight to locate it. It's often near the linkage that connects the transmission shift lever to the transmission.
Because it's on the transmission, accessing it might require working under the vehicle. Be absolutely certain the vehicle is safely secured on jack stands before you begin working underneath it.
Remember safety first! If you're not comfortable working under your vehicle, take it to a mechanic. Mislocating or improperly working with this switch can be dangerous.
