Widow benefits what to report

I'm fairly new to this benefit I got a form SSA-1099-SM. I completed the form and it came out box 5 had 6,635 I did the multiply by.05 $3,317

I added box B,C &D it came out $331.75

Do I put the $6,635 for net benefits or do I put the $ 3,317 ? 

Since all the $6,635 isn't taxable I'm confused