How Do I Find Who Last Edited a Record or Table in a Database? I believe that I have most of the work done for whoever wants to tackle this question.

I have the following query built:

USE MyDataBase;
GO

SELECT DB_NAME(ius.[database_id]) AS [Database],
       OBJECT_NAME(ius.[object_id]) AS [TableName],
       MAX(ius.[last_user_lookup]) AS [last_user_lookup],
       MAX(ius.[last_user_scan]) AS [last_user_scan],
       MAX(ius.[last_user_seek]) AS [last_user_seek]
FROM sys.dm_db_index_usage_stats AS ius

WHERE ius.[database_id] = DB_ID()

GROUP BY ius.[database_id], ius.[object_id];


If possible, how do I add which user it was that made a change?
You cannot achieve this if you do not have a historical or archive table that store this data. You have to create an AuditDb and create some DML trigger.

OR 

You have to use a third-party log reader (if log is not shrinked) like ApexSQL LOG