Using your camera in auto focus is by far the easier option and we all use it. Many cameras have different autofocus settings, place the focus box in the center and make the box as small as you can. You should find the camera will focus more quickly because it is only trying to focus on a small part of what it sees.
You may want to compose the photo without having what you focused on in the center. This is easy, to do this just hold you finger down on the auto focus button and once it has focused keep it held down and move the camera and compose the picture, then press down fully the button and take the shot.
In fact most images look better when the central focus of the image is not exactly in the center. This I will explain more in ‘composition’. If you are taking a photo of a fish and it is a major part of the photo make sure to focus on the eye, it has to be in focus. Once in focus you can compose and then take the shot.