You'll need to consult your owner's manual. It will show you exactly where the fill plug is located and the proper procedure for checking and adding transmission fluid. Don't rely on generic information; this is crucial for your transmission's health.
Warning: Using the incorrect fluid or adding too much can damage your transmission. Always use the type and amount specified in your owner's manual. If you're unsure about any part of the process, it's best to have a qualified mechanic perform the service.