Enter form SSA-1099 where?

I tried to do my disabled son's taxes.  I called but it e-mailed me instead.  I asked where to enter form SSA-1099.  There was no place to enter it when I went through the income section.  Once I reviewed it, there was a place to enter social security.  I did it but in the end, it says there is no income.  Does that mean he does not have to file?