give more specifics. Anyway, is this a school project? Otherwise, buy 'em, they're cheap.
If it's school, then a voltage regulator suited to the ratings of the battery should do it, powered by another battery or something. Or if you want it to be solar-powered, or generator powered, or powered from mains, that's a different story. So... give more specifics.
1. this is my college, minor project; to be made before/till 15th april
2. well, i mainly have thought it to be a charger which will take suppy form computer's usb.. that is, output of computer's u.s.b. will go to the circuit.. it will do something (procesing of input), and then when i connect NOKIA MOBILE to it, it will charge it..
3. you know what?? nokia usb chargers are not available.. so i am making this to produce a nokia mobile usb charger..
4. any more information required?? please tell...