It says I have an excess contribution to a self employed retirement plan but it doesn't tell me what the excess is so I can withdraw it. Where would I find that?

The maximum contribution to a SEP retirement plan is 25% of your net self-employed earnings up to $69,000.  You will need to figure out what 25% of your net earnings is and see if the amount you contributed is greater than that.  If it is the amount that is greater is the excess contribution.

@wendytoups 

Examine TurboTax's Keogh, SEP and SIMPLE Contribution Worksheet.