Hello again. First of all I want to thank you for trying. I did find it in the end but it was a real pain in the ass. Below I'll explain how I did it for future reference.
1) I checked the "one click installs" but unfortunately nothing happened. The link just says that out of the "X" number of programs dreamhost provides under the "one click install" service, you installed these "X" programs and nothing else. In order to find a php file you need an ftp client
2) I downloaded an ftp client: Filezilla. I prepared the necessary properties[color=#FF4500]*[/color] and pressed "quick connect".
[color=#FF4500]*[/color] = which are:
[color=#0000CD][b]The host[/b] = Your domain name.
Your ftp username = Every company which provides hosting it also provides an ftp service. Dreamhost creates by default an ftp user based on your dreamhost account
Your ftp password = The ftp one, not your hosting password
The port number = I put 21. It's the only I know (:P)[/color]
3) After the connection I found some irrelevant to me folders and a folder which uses as a name my domain name. E.g if your domain name is "my cool site" then the folder is named as "my cool site".
4) Enter in there (in "my cool site" folder) and you'll see 3 folders (WordPress version 3.5.1 = April 2013) and a lot of various files.
5) Search for wp_config.php. Edit it according to your preferences. (NOTE: EDIT IT ONLY IF YOU KNOW WHAT TO DO!)