can't get this thing to work

I must be dumb as a rock but I uploaded my first website (finally after a few mistries) and got it to working. Then I closed that link and opened another link to a different website and tried to load another set of data. the data ended up on the previous website and I lost the original data on that website. Tried it 3 or 4 times and ended up with the same resultants. What am I doing wrong?