First you have to use something like security assist to allow users to log in. Once logged in, you will have their UserId in a session variable.
You would create a table called cottage_favorites... that table would have a unique key, autoincrement field, call it FavoriteID, then it would have FavoriteUserID to save the userid from the session of the logged in user and FavoriteCottageID to save the id of the cottage that the user wants as a favorite.
Your "add to favorites" button will insert into the cottage_favorites table, and your results page will use the session userid stored to filter and show the favorites that have been inserted for that particular user by creating a recordset with an INNER JOIN between the cottages and cottage_favorites tables.
