You have to install the module audittrail. You will have access to audit configuration in the reporting menu.

Install the Audittrail module. After installing it, you will see it in the Reporting menu an Audit menu item. To track user activity you need to create audit rule. Audit rules are specified on a particular model that you want and assign user that you want to track that activity. To activate the audit rule you need to first 'Subscribe' to the audit rule.

Example: Create an Audit rule- Sales orders;

               Add object-Sales order;

               Add the users be tracked;

              Save and subscribe;

             Login as user to be tracked and make changes to Sales Order, then login as Admin to see the Audit Logs.