How do I get to Form 8949 from within Turbo Tax?

My 1099-B form for sales says under Additional Information "Return of Principal".  When I enter the data from my 1099-B for the sales, Turbo Tax adds the amount to my total annual income.  This is not new income because the value of my account is not increased.  How to I indicate that the proceeds on my 1099-B are not new income?