A side gate is no different to a standard garden gate apart from it is normally placed at the side of a house or property instead of in a run of fencing, restricting access to the rear of the property via an alley or path.
Side gates are installed the same way as a usual garden gate would be installed; using two posts and then hanging the gate on one of these posts and it closes against the other. Sometimes if the alley or space down the side of the property is tight then a wall plate is used. A wall plate allows the gate to be installed up against the wall.
Side gates will commonly be exposed to strong winds as gusts pick up down the side of the property or try to force through the opening at the side of the house. If strong gusts of wind are a major problem then gates that allow wind to pass are available. Some of these gates include Jaktop, palisade, paliframe and even trellis gates are an option.
If privacy is also an issue but it would be good if some wind could pass through the gate then Hit and Miss, where the pales overlap each other so you can not see through them or Venetian gates are options.