LED conversion


Now my question is,,,,,what kind of power converter do i need? I went to radioshack and asked, the answer that the women gave me was "those cars didnt come with led's you need a light bulb" so i figured i wouldnt try to explain any more,,,,she was clueless...
I know there are different volt/amp/ led's so if you know what i need can you post the specs of the converter i need, so i can walk in somewhere and say "I need a converter with these specs.................... 15 white led's with these specs............................."


