The words 'left' and 'right' in politics come from the French Parliament, known as the Estates General - as Paddywak suggests above but before the Revolution, as I understand it.
There, the nobility sat on the King's right-hand side and the rest on his left. The nobles, of course, wanted things to go on just as they always had...ie they were 'conservative'. The others wanted change...more fairness in wealth, ownership etc.
Nowadays, the same idea applies to modern governments. In the UK, the Conservative Party is right-wing and the New Labour Party is left-wing; in the USA, the Republicans are right-wing and the Democrats are left-wing.
Perhaps you could run a Google search using "estates general" for further information.