Dear Shakeel
To apply for Indefinite Leave to Remain in UK, you must be in UK for at least 2 years from the first time you entered the Country, you can't apply before that except you have 28 days to apply before your visa expired. The original document you need it with your application are:
Passport
Marriage Certificate
Utility bills such as Electricity, Gas, Phone bills
Home office documents shows your current address
also you have the pay the fees
any documents form official sits such as HM Revenue, Tax etc..
for more information I advice you to log on to the Home office web site
www.ind.homeoffice.gov.uk
Best wishes
Jumaa