Someone with a wordpress site in lets say www.thess.com asked me to change the theme, so i thought it would be safer to first create a second wordpress installation in lets say www.thess.com/welcome and then, after having moved all of the content to the new installation and calibrated the theme, move the new installation to the root directory.
So, i have reached to this point but i don't know what is the safest way to move www.thess.com/welcome to www.thess.com, apart from taking a backup of the files and database of the first installation.