I won't be able to install my web editing program until friday. Is there a way I can directly edit my site using my browser until then?
I don't know... but I think all the operation system have a ftp program, like ftp.exe on windows...
Also, there're servers that offers webftp to other servers...
No Setup Programs (in spannish, yes... I'm from Spain)
If you're just changing some text on an already created page, you might consider saving the page to your computer with your harddrive [File > Save As (w/ IE) or Save File As (w/ Firefox)] and making the edit using notepad which is on every Windows computer.
You can do FTP with just your browser by clicking the "Upload to Web" link on your web panel under Domains > Manage.