Everyone says "don't use root" but never really tells you why... when logged in as root in my early days in Slackware (I've never done more than dabble for a few months at a time) I've:

Moved my entire filesystem to under the /etc directory (mv /* /etc)...

Deleted my kernel (don't ask)

Completely hooped any chance of booting because I edited too many startup files at once and broke the file format on multiple ones.

Almost turned my monitor into a paperweight trying to force a higher hSync back when you had to have XWindows probe your monitor. (There were warnings about monitors possibly catching fire).

So in a nutshell, grab a live version of linux like Knoppix or Ubuntu, boot it on your desktop, and play around. Look up shell commands, try them out, become comfortable. After that you'll be able to use the root user to mod your 770. Before that, you're playing with fire.

(Oh, and for the record I liked to run UMSDOS as my FS way back when, so all I had to do was boot back into DOS and move the directory back or copy the kernel back to the root directory from my UMSDOS boot dir. So far as the startup script learning experience, or my how-to-turn-a-monitor-into-a-marshmallow-warmer-in-one-easy-step one, the monitor still worked. The scriptage lead to a reinstall.)