No permissions for Database, but have .mdw file. How can I edit it t gain acces to Db?

I have an .mdb that a previous Access developer created. Unfortunately, the developer left no documentation and no security credentials.  : (  My boss has charged me with cleansing some of the data from the database and changing the security so that that databse can be used.  I do not have admin rights (or the admin password) for the database.  An MDW file was set up for use with the database. I do have the .mdw file.

I need to know how I can open and edit the database and make changes to  the security.  I don't have much experience with Access, so please be gentle.  : )

Thanks in advance.