This will depend on how the website was built. If it has been built as a static website, then no, you can’t update it yourself, you will need a professional website designer to do this for you.

If, however, you have chosen a website that is dynamic and the content is controlled by a Content Management System (CMS) then yes, you can update the information yourself. In fact, that is why it is designed and built this way. You will need to inform me at the very beginning of the design process if these kinds of updates are required and if training will be needed. In some cases, you may want the designer to maintain the website for you regardless.