Could support/ssdi

So I have a quick question how does one go about needing to quit a job and apply for ssdi (social security disability insurance)? Illionis my husband is putting in his 2 wks he suffers from Ms ( multiple sclerosis) and has really found it hard to continue to work so what happens does he go to modify in court bcuz with out him working, she gets no child support or insurance for the kids anymore know any info or can point me in the right direction with some correct info thanx so much..