What is a job of a councillor?

I'm just wondering, coz there are 6 people who I know who are councillors my neighbour and local big mouth farmer, who does nothing but moan, especially at BT, another two from town, who work at the council office with posh cars and moaning to the local press about cuts and how another councillor or AM or MP is doing so badly, and hardly does nothing for you, for example, theres a footpath near my house that needs raparing coz its dangerous and erroding to the river...instead he and the council pays thousands on re-tarring a road that doesn't need tarring, and changes a free car park into a pay carpark, or ordering people to make signs and stuff, spending thousands on helping scroungers on the dole and raise rates and council tax...the rest are old and seem to talk much and do less...if I wanted to be a councillor do I have to be a member of a government like AM(assembly member) or MP? and who exactly is the head of the council? for example gwynedd council..an AM? or all of them?