Excel 2007 : Help with macro for password

Hi everyone, i'd like your help to solve a problem i have.

I am no programmer but for work i need to set up an excel file with 4 sheets;

1-the first sheet must be protected with password and visible ONLY for who has the password.
2-opening the excel file the user (whoever he is) must see the sheet 2 as first sheet.
3-when the user clicks on the sheet 1 he can see an empty page (hidden all columns). He needs then to enter the password: if the password is correct the sheet 1 will appear properly, if not, it will stay locked with all columns hidden and no chance to modify it.
4 and main problem- i want to put the password once and never again until the excel file stays open. I had a macro that did the first 3 steps but i lost it and i had to re.enter the password every time i clicked on "sheet 1", which i don't want to do.
5-many people use this excel file, i need to hide the macro with the password for the sheet 1.

I work in an office, my job is not about solving this problem, i'm just an accountancy man, that's why i would really appreciate your help.

thanks!

edit: easier solution you could give me:
i need this behaviour:
i open the excel file and i can see sheet 2, 3 and 4, while sheet 1 is very hidden (or how you say it, i mean you can't even see it). I need a button on sheet 2 that if i press it i will need to enter a password. If the password is correct sheet 1 will be visible (and editable) until i close the excel file. After that i need to hide the VBA code for the button so that nobody can see what's the password behind it.
I think it's really easy for you, this second way.