When to fold pocket pair in Limit Holdem?

in a Limit holdem game...a very LOW Limit holdem game, in a casino. What is the time to play a pocket pair and when is it time to fold. Most people see the flop and dont raise in the very low limit holdem games -- so does that mean i should be playing low pocket pairs, call or raise if i hit my set on the flop and fold if i dont it....or do i need to fold them pre-flop.
can anyone break this down for me and give me infor as to the positions to play them from too please?

thank you!

generally you should fold small pairs from EP in limit but if the game is very loose passive you can get away with limping these hands. you just need to be fairly certain multiple players will limp behind.
i wouldn't get in the habit of limping these hands in EP... only if you find yourself in an extremely loose/passive game.

this chart is very good imo. it shows how many limpers you need in the pot to play certain hands.
http://www.pokerschoolonline.com/articles/Pre-Flop-Play-in-Limit-Hold-em?page=2

at the bottom it explains how to read the chart.