User management in android application (using eclipse)

I am a new programmer.
I want to implement an android mobile application for appointments for a medical center using eclipse.
My application will have 3 users:

• Administrator who enters available dates and times for drs
• Clients who choose the date and wait for a confirmation via mail
• Drs who can see all the appointments reserved

My problem is that I don’t know how to manage users.
Is there any specific tool in eclipse?

Any article or link to help me solve this issue?
I am using the version 4.2.0 of Eclipse.