Changing User Permission

I need a script for changing user user permissions on each database, how do
i achieve this?
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Eager to LearnWhat exactly are you trying to do? Look up GRANT, DENY and REVOKE in Books
Online for a start, then create a list of database objects, a list of users,
and goup users with similar requirements.
Based on the groups of users with similar requirements, create SQL database
roles with users as members, then grant privileges to those groups as
required.
For better help, please, provide bettter specifications.
ML