Security in Split Database 2007 version

Question 1:
I have created a 2007 Access database where I need to give certain groups a
user and password to access data. Group 1-Management they can see all data
and reports. Group 2-Managers & Employees they can only see data for their
assigned categories. Lastly, admin.

Group 2: Certain employees can only access data assigned to Category 1 and
certain employees can access only data assigned to Category 2.

Question 2:
Do I have to split the database so that I can set this security up? or Is
there a way that I can leave the database as one and simply re-create
something like the User-Group permissions feature?

Please help.
Thank you in advance