You can manually create appropriate DML triggers, but that requires manual set up of auditing repository too. On the other hand, the process can be automated using ApexSQL Audit, an auditing tool for SQL Server databases which captures data changes that have occurred on a database including the information on who made the change, which objects were affected, when it was made, as well as the information on the SQL login, application and host used to make the change. It stores all captured information in a central repository and exports them in print friendly formats
The technology which ApexSQL Audit uses for auditing is based on triggers. These are created using its visual interface, without any need for T-SQL knowledge.
Disclaimer: I work as a Product Support Engineer at ApexSQL