Moving from one server to other

Hi everybody. first of all excuse my english. I dont know it very well.
So, let me tell you what my problem is:

I have wordpress installed on mediatemple and i decided to move everything on dreamhost. I didn’t know hot do to and i simply “Copy” my website on my pc, and after that i uploaded on dreamhost hosting. I changed de wp-config.php, database mysql and all of that, but, when I entered on my website, it says something like “hello, enter your username and password, and if you think that there was more steps, then sorry to dissapoint you.” – welcome message from wordpress (the same one when you install for the first time wordpress). Anyway, i pus the username and password, and now i don’t have any of my articles, nothing. I have default theme witch i just changed with the one i used to have. So, my question is: What can i do to reappear everything how it was? Thank you very much