NTBCC has created this document to explain in simple language how it works. Here is the web version. It is also available in PDF format.
In brief, NTBCC is created under Section 51(2) of the Local Government (Scotland) Act 1973, which provides the statutory basis for the establishment of community councils. This, and the Edinburgh scheme for CCs state that
In addition to any other purpose which a community council may pursue, the general purpose of a community council shall be to ascertain, co-ordinate and express to the local authorities for its area, and to public authorities, the views of the community which it represents, in relation to matters for which those authorities are responsible, and to take such action in the interests of that community as appears to it to be expedient and practicable.
And this is what NTBCC aims for, as well as it can, given the limited resources it (and other community councils) have.