Want to start my own painting business,doing small jobs for individuals who want their house painted,bedrooms,livingrooms,bathroom etc.

Whereabouts do you live? Where I am (England), people are often referred to as 'odd job men' who do this sort of work and no particular license is needed to do it.

Depends on where you live. Contact your local licensing dept in your county or city. Are you going to get liability insurance and be bonded? That costs a lot more!