Why do I get error(s) about permissions ?

One of the very first steps before actual installation takes place, is to do a check to see if certain files and directories can be read from and written to by the "web-user" (the username used by your webserver).

Failing to have appropriate access (read, write, execute) to these files and folders/directories, will prompt you to fix it before continuing with the installation.

You will see the number of error(s) found, and exactly what file/directory each error is related to.

Once the permissions are as expected, you will be able to continue installation.

You can either set/change permissions using f.ex. your FTP-program (if you install on a server that's hosted by your ISP), and/or if you have terminal access (either directly or using f.ex. telnet).
 

Here's an example where all permissions are OK:

02-11-2012