Check Lower berth quota in indianrail.gov.in and if it available then go to IRCTC . Choose GN and as usual fill all the detail and it will show the GN quota Current status . Ignore that and click on Book and pay and when your ticket Come out it will have confirm berth. ( System auto give lower berth to a Senior Citizen if he is traveling alone and a female above 45 years if she travel alone)
Please note If male then above the age 60 and if the female then it should be more then 45 and also note No other passenger name should be there in the form.
Thus...
more... lower berth quota which is also known as SS quota .