Get WinMPQ and carefully use it to open up the game .mpq that has the campaign you want to yoink. Look for *.w3x or *.w3m and scroll until you find the map you want. Extract it. Do *NOT* delete or edit anything in the .mpq, only extract from it. No, don't edit it. No, don't delete anything. No, don't insert anything. Stop that. Hands off. Extract only.