Custom camera profiles need to be placed in the user folder location shown below. You will also need to close and restart LrC to load them. Keep in mind camera profiles are camera model specific and will only be visible with raw files from that camera model.
Can you be a bit more specific? It sounds like you are not talking about color management profiles (icc-profiles), but camera profiles. Do you have a raw file selected? Most default camera profiles are for raw only, if you select a jpeg or tiff file, then you will only see a generic 'color' and 'greyscale' profile. Creative profiles often work for both raw and non-raw. So what profiles do you want to add? Did you buy or get extra profiles?