writing http login system

can anyone help me write a php script to verify login tokens(username,
password, company_code), if a user with specific identity, for example,
admin user is root, login name is root, password root, company_code local &
has privilieges of adding, deleting, modifying user's profile(s), login
successfully, redirect him/her in identity-dependent page(admin.php) using
session features in order to store his/her login details per session?

thx a lot!