Hey,
The simplest way to use the Normalize method is how @ptrblck suggested.
normalize = transforms.Normalize(mean=[0.485, 0.456, 0.406],
                                 std=[0.229, 0.224, 0.225])

transform=  transforms.Compose([
    transforms.ToTensor(),
    normalize,
])

but you then pass the transform to your custom Dataset as a parameter and after getting the image you
just apply the transform on it. here is a simple example:
class CustomDataset(data.Dataset):
    def __init__(self, transforms=None):
        self.transforms = transforms

    def get_image(self, index):
        raise implement!

    def __getitem__(self, index):
        image, target = self.get_image(index)

        #perform transform
        if self.transforms is not None:
            image = self.transforms(image)

        return image, target

    def __len__(self):
        return len(self.dataset)