i want to start a cleaning service company.help me on how to write a business plan?

Check out our Bplans article "A Standard Business Plan Outline" by Tim Berry at:

http://articles.bplans.com/writing-a-business-plan/a-standard-business-plan-outline

This will give you a rough idea of how to write a business plan. More articles on business plan writing are also available at:

http://articles.bplans.com/writing-a-business-plan