Many affiliated clubs conduct regular classes. Some are for the complete beginner and some are for the improving player.
Supervised classes are offered at many venues so that players can gain confidence before moving on to more challenging sessions.
Go to a few of these to get your feet wet and then move on to play in regular deplicate.
The rule of thumb for trying to play in real duplicate sessions while you are still doing supervised sessions is to play 3 times. If you score over 40% twice, you are doing fine.
If you keen and a self-starter, you can use online bridge or playing computer programs, such as Bridge Baron or Jack to help you after you have been taught the basics by a good bridge teacher.