Time is running out; My taxes are incorrect. Help!

[Etric]

Someone filed my taxes for me, without taking into account my gambling winnings. They used telefile, so I am trying to figure out what to do. Has anyone been in a similiar situation? If not, does anyone have any advice on what I should do? I want to pay taxes on my winnings. Do I just need to file a 1040X to amend my tax return? I did not make that much money (around 4k) and I will not be itemizing my deductions. Thanks for you help.