how red coloured leaves prepare food?
CRed or other colored leaves carry out photosynthesis. The chlorophyll is there but masked to our eyes by the red colour of the cell walls. It causes little or no hindrance to the wavelengths that cause photosynthesis. If you hold a red leaf up to the light, you will see that it is distinctly greener than when you look at it by reflected light. This shows that the red pigmentation on the surface is not really obstructing much (if any) of the light needed for photosynthesis.
The red/orange colour of dying leaves (and in ripening fruit) is caused by the change of various substances (including chlorophyll) into carotenids. Chlorophyll is always green (but fluoresces red under certain circumstances) because it strongly absorbs the upper and lower ends of the spectrum and reflects green.