To find it:
1. Consult a repair manual: A Haynes or Chilton repair manual specific to your 1987 Honda Accord LX will have diagrams and precise locations for all drain plugs. This is the best and most reliable method.
2. Look for a bolt: It's usually a smaller bolt than the engine oil drain plug, and might have a slightly different shape (e.g., slightly recessed). It's likely to be magnetic, like most drain plugs.
3. Be careful: The area is usually greasy and dirty. Wear gloves and eye protection. Don't force anything.
Remember, working on a car's transmission can be complex. If you're not comfortable doing this yourself, it's best to take it to a qualified mechanic.