In that case, follow what Madhivanan suggested - i.e., add a new column for keeping track of updates/creates like shown below:
ALTER TABLE YourTable ADD YourTimestampCol DATETIME DEFAULT (GETDATE()) NOT NULL;
Then, add a trigger like this:
CREATE TRIGGER dbo.UpdateYourTableTrigger
ON YourTable FOR UPDATE
UPDATE YourTable SET YourTimeStampCol = GETDATE();
GOWhile you are at it, depending on your requirements, you may also want to add an username column so you can keep track of who made the updates to the data.