First, use a flash, either using the built-in flash or an external flash or lighting set up. This can be an expensive process and not very likely to work for beginner photographers. You can also try shooting at a lower shutter speed. This will allow the image sensor to stay open longer thus allowing in more light to compose your image. For handheld photographers this can be a tough act as it may cause some motion blur, use a tripod or level surface to keep your camera still. Another tip for eliminating high ISO is shooting with a low aperture, this makes the sensor larger, allowing more light in. Most zoom or telephoto camera lenses only allow you to shoot as low as 3.5-5.6 F stop, this is a fixed aperture range. Prime lenses have lower ranges of F stop from 1.2-2.8. By shooting at a lower F stop you will create a deeper depth of field. This means that only your subject will be in focus and the background will have a smooth blur so be mindful of this.