First, I wasn't able to create a symbolic link. Being in root, I tried:
#ln -s ./html/files files
That created a link inside the existing folder (outside) targeting at the files folder inside html. It didn't solve the problem. It seems that I can't create a link named files if there's already a folder with that name. It looke like: root/files/files, and it can't be accessed. Then, I deleted the files folder 1 and the link just created, and I tried again:
#ln -s ./html/files files
Apparently it did it. It takes me to the folder inside html. However, when I try to download files, I get a "403 Forbidden error", although before I was able to access to files outside html. Besides, if I had just deleted the files folder outside html, (without making the link), I would've gotten the same error. Apparently, without the files folder outside html, files folder inside html is looked for.
Next, I created another folder inside html and named it "uploaded", and configured drupal to upload files into this folder. That did it. It seems that drupal got confused with files folder 1, because SME server by default takes root/files to the folder outside html. I hope I won't have more problems; otherwise, I'll come back.
Yersin.