Why is my Mac not starting,,?

Problem started with freezing screen, had to restart holding power button. later i started having startup problem. Screen suddenly goes white when the thing is spinning under apple logo during startup grey screen. Rarely (after 5 or more restart attempt) it passes that phase and i couldn use it. but now battery doesnot charge and same thing happens when i try to start computer by connecting charger.. any suggestions most welcome. and it ejects installation CD automatically when i try to run from CD. I have got 2cds may be i do not know proper way to use my CDs. Suggestions Plz???