I forgot to add a dependent before going through the tax questions, when I did later it didn't chnage anything. As if I recieved no credit for that dependent. I would like to know why and/or how can I see the information and how it is used?

[KenH1]

You can verify your dependents by going to:

My Account (top menu), then

Tools 

View Tax Summary (Under Other helpful links)

Exemptions (5 line) should be $4050 for each person claimed, including you, a spouse, and dependents.

If the $4050 for your dependent is there, but your refund still didn't change, then your taxable income may have already been at zero. 

Also, when you enter a dependent, be sure to answer the questions that follow.