I want to carryover my cost in 2018, how do I fill the form schedule d in turbotax when I filed 1040NR last year without form schedule d?

I filed 1040NR last year because I was in OPT before July 2018, but I'll file 1040 for 2019 since I got H1B after July 2018.  I can find "Net short-term capital gain or (loss)" and "Net long-term capital gain or (loss). (2018 Schedule D, line 15)" from my 1040NR form. But I don't know how to fill "Allowable net capital (loss). (2018 Schedule D, line 21)". Anyone could help? Thanks a lot!