Checkboxes HELP!!!

I am having trouble with the query and output. Here is the scenario. I have a 3 tables (locations, categories, location_categories.) There are 20 locations, and 5 categories which are checkboxes. The categories are (lube, paint, brakes, tire and repair). The display form selects all locations and categories. Multiple category selections can be made for each location. The action page takes the submitted information and adds it to the location_categories table. I need to be able to query and output each location with all five categories and show the checked categories for each. The location_categories table has these columns (location_category_id, location_id, category_id).

How do I write the query and properly display it, When Adding or Editing the form.