get form 1045 from irs website. use schedule A. CAREFULLY read the instructions for this schedule and form
https://www.irs.gov/pub/irs-pdf/f1045.pdf
https://www.irs.gov/pub/irs-pdf/i1045.pdf
by the way have you already filed your return for the year the NOL occurred? if not, you can elect to carry forward the NOL or not if you do not make the election on a timely filed return, you must carry the NOL back to the second year prior to the NOL year recompute what's left in any and then carry that to the first prior year.
