Ah yes the good old pub quiz.
Usually this is played in teams, so you go along with some friends. Each team pays a small entry fee to do the quiz, and you are given some sheets of paper to write the answers on. Sometimes there will be a sheet with photos of people and you have to write in the space provided who the people are.
There are several 'rounds' - usually subjects like pop music, history, geography etc. - the quizmaster has a microphone and reads out a question. Your team decide (quietly so you can't be overheard by the next table!) what the correct answer is and write it on the paper.
When the quiz is finished, all the tables swap their answer sheets (or hand back to the quizmaster who will hand them out to the other teams) and the quizmaster reads out the answers, and you mark the answers on the sheets you have been given, awarding points for each answer according to the quizmaster's instructions. Once the marking is finished, all the answer sheets are handed back to the quizmaster and he will announce the runners up and the winner. There are usually cash or beer prizes for the winners.
Even if this one is organised differently to how they are usually done here, I am sure that you will have a great time, they really are fun!