edit website

can someone help me, I had a website made, as I am a complete novice, and this is just for small business, the person who designed said I could edit myself and change what I wanted, they showed me the website and all I had to do was change text, pictures etc as I saw them, now they have disappeared and I cannot find how to do it, each time I try to edit it sends me through to all this website gobbledgook which I cannot understand HELP