Excel to ask user name and password using macro!!

[meus]

Hello Friends!!
Greetings from NEPAL..
I have a workbook with 5 sheets(Sheet1, sheet2 and so on)
What i want to do is, i want to assign my workbook a macro which if user opens, then asks for a USER NAME and PASSWORD...

Then after:
If the user name is "AAA" then open Sheet1 and hide other sheets,
If user name is "BBB" then open sheet2 and hide other
If user name is "CCC" then open sheet3 and hide other sheets and so on for 5 sheets with distinct user name.

Please if anyone could help me, really appreciate...
Thanks in advance..