Time Machine/Backup Problems

oh my goodness....I just wanna scream!!!
ok, so my system preferences seems to be gone & several of you suggest doing a clean install, after other suggestions didn't work.
so I get an external HD to back everything up to and I can't seem to figure it out. When I click on Time Machine, it says it cannot find it.

when i plug in the other HD I originally backed everything up to, it says there's only a small amount of space left, yet it doesn't allow me to even open ANYthing.

I don't know what to do & I'm beyond extremely frustrated! Mostly with myself for not knowing more abt computers in general but good God, this is just ridiculous.

I am stuck and not sure what to do.....should I just put my laptop in the toilet, hit my head up against a wall and scream????

please help
thanks
dawn

First up can you see the external in Disk Utility when it is attached? If so you will have to format it Mac OS Extended (Journaled) and then in Partition choose Options and make sure GUID is set up.

If you can't see the external in Disk utility double check the connection cables sand see if the case has a separate on/off switch. If still no joy the external drive may well be dead.