use this code. Though you must have got a file named app.java when you downloaded .zip of physics body editor. This code is from that file only which uses .json file from the editor.
// 0. Create a loader for the file saved from the editor.
BodyEditorLoader loader = new BodyEditorLoader(Gdx.files.internal("data/test.json"));
// 1. Create a BodyDef, as usual.
BodyDef bd = new BodyDef();
bd.type = BodyType.DynamicBody;
// 2. Create a FixtureDef, as usual.
FixtureDef fd = new FixtureDef();
fd.density = 1;
fd.friction = 0.5f;
fd.restitution = 0.3f;
// 3. Create a Body, as usual.
bottleModel = world.createBody(bd);
// 4. Create the body fixture automatically by using the loader.
loader.attachFixture(bottleModel, "test01", fd, BOTTLE_WIDTH);
bottleModelOrigin = loader.getOrigin("test01", BOTTLE_WIDTH).cpy();