Editing images is something anyone who maintains a website will have to do from time to time. These days most small businesses have a website with a CMS so this means they will be maintain their site themselves for the main part.
The first thing to know when uploading an image is some image files are huge (ones off a decent digital camera might be 5 meg in size). We would suggest trying to keep any images loaded onto your site under around 50 kilobytes so to do that you will have to do one (or both) of the following.
Change the image resolution
Images straight from a camera will be high resolution and suitable for printing large copies. They might be 300DPI (dots per inch) or more. For the web 72 DPI is sufficient so reducing the resolution to 72 will reduce the file size significantly and it will still look more or less the same on the web.