We have installed Tridion for our enterprise and as a Content Admin/Author, I need some tutorials on Access Management and also if possible a link to the Manual.
Welcome to the Tridion Stack Exchange site.
You have done the right thing in asking about Tridion CME security and doing some research before diving in. Tridion security is very flexible and powerful, but this does mean that you can easily tie yourself up in knots if you do not plan properly!
The main thing to be aware of is that it is focused around
Permissions. If you set these up well at the start, and test them thoroughly, then the security set up will serve you well. If you try to cut corners or plan to 'come back and fix it later', then it can cause you a world of pain.
As well as looking through the security section of the online documentation (login required), I would strongly recommend that you read Alvin's SDL Tridion CME Authorization blog post and and browse over the 'authorization' tagged questions on this site.
You may want to explore below links (Requires Login)
Releted links are below for Access Management: