Retirement tax questions

I am not trying to be a pain I just need help understanding this. To answer your question, no, this is my first distribution that I have ever taken. Maybe I'm wrong but I don't think I should have to pay any tax on the $4000.00 as I didn't defer this amount in previous years which means I already paid tax on that money. So do I have to enter the remainder of my IRA on line 6 of the 8606 form or do I enter 0.