If you are ordering a bottle of wine, your waiter or wine steward will present the wine to you. Next the waiter will uncork the wine and give you the cork. Basically, you want to check the cork to see if it is wet, which signifies that the wine has been stored properly on its side. The waiter will then pour a small bit of wine for you to smell and taste. If the wine is acceptable, the waiter will then serve the others around you and then refill your glass.
Good restaurants go to great pains to train staff who are knowledgeable about wines.