How to split an FFT into specific bands.

    May 01 2014 | 2:41 pm
    Hi there,
    i have built an EEG which connects by a jack lead, this then goes into the computer and i have used an FFT to give me the data. What i know want to do is split this data into specific bands. for example 0-7hz, 8-12hz, 12-30hz, 30hz upwards. I would like this data to be represented as a number stating the intensity of the spectral activity within a band...
    Any suggestions will be appreciated.
    N.B i have been looking into the ifft, pfft etc, and have experimented in trying to get them to do what i want, however, i cannot get the data expressed as a number nor can i seperate it into my desired bands.