To get the whole of a subject in focus, where the subject has depth, you can do two things.
One way is to set the size of the lens (its "F number" which goes from about F1.9 (lens aperture wide open) to F32 or so (lens aperture closed to a small diameter). This produces a greater depth of field (=more of the near and far away parts of the subject will be in focus). Your camera has a setting for setting this manually, called "Aperture Priority". This means that you choose this, probably from an menu, (or a selection wheel). This means that when you set it to a certain F-number (the higher the better, say F32), the camera will close the lens to that small size and then set the shutter speed to a relatively long time because the big F-number (=lens aperture is small) lets less light into the camera. You might need to use a stronger light to give the camera the chance to choose a shutter speed high enough for the camera to be held in the hand (say about 1/30 second, 1/60th better to avoid movement). If the camera chooses a slower shutter speed than that you will need a tripod to keep the camera steady.
The other way is to hold the camera about two feet away and set the telephoto to enlarge the image sufficiently in the viewfinder or screen. This usually works because with the camera being further away, the difference in distance between the back of the subject and the front is a smaller proportion of the camera-to-subject distance, so the camera can produce a sharp image for the whole subject. Also, doing it this way gives better perspective. This is because the nearer the camera is to the subject, then (as mentioned above) the difference in distance between the back of the subject and the front is a smaller proportion of the camera-to-subject distance. Anything that is nearer always appears bigger to the eye (and the camera) than something further away (obviously). The greater the difference in distance between the back of the subject and the front, the greater will be this distortion, and models being small, it is often obvious (e.g.., in an aeroplane side-on, the nearest wing can appear too large. When looking at full-sized objects outside (houses, cars etc.) the brain compensates for that but not in a photo. For that reason, professional photographers use a longish lens when doing face-on portraits of women, to prevent the nose appearing enlarged.
In both cases you will need to switch off auto-focussing (in a menu somewhere) and set the focus (by turning the focussing ring on the camera lens) and checking in the viewfinder or screen that all is in focus.
Hope this helps.
Adrian