How do I copy 1 external HD to another?

Question

I was just at the Genius bar who reformatted my new WD 1 TB drive for use w Time Machine.
He also showed me how to copy my old Seagate HD (that is getting noisy so want to back it up) to the new WD drive.
W both HDs plugged into the USB ports of the MacBookPro,
It was done by dragging the Seagate to the WD. But I can't find the screen that he was in where he showed me to do it.
The screen just showed the 2 HDs w the sub name of the drive underneath each one. So it didn't look like a regular finder screen. As I recall it was prettier than a finder screen & it had green coloring.
I tried to call the store to see if I could talk to the Genius but they sent me in circles, transferring me to Apple Care w out telling me they were doing so & then I got a call director that asked for my serial # which I found & read to it, but it didn't seem to find it associated w Apple Care. But when I called back I did ask how long it lasts & he said 3 years so I should still be covered.
I'm realizing that I should have written or typed up exactly the steps but it seemed so easy. & it will be once I can find the window or screen to be in to do this.
I remember now that it showed the 2 folders Backups.backupdb & home folder contents in the Seagate & I thought in the WD drive.
But I'm also wondering since I think it has some other things that were copied to the drive via drag & drop, but I'm not seeing them now--some other things that I had copied to archive them, rather than through the back up process.

Answer 1

Update. From Finder window showing name of my computer, it showed devices in the bar on the left, I selected my Seagate (old) external HD in column view. & then in the columns it showed 2 folders, Backups.backupdb & Home folder contents. I selected both of those & dragged them onto the WD icon & it seemed to be copying.
But then I got an error message something about action can not be completed because it has back up & non backup items.
I do have both back up items as well as other items that I wanted to archive on the drive. It seemed to have been working fine all this time since April 2011 when I started backing up.
I'm also trying to look at the backups in the finder window to see size but the size isn't showing.
Does the drive need to be partitioned if I want to have part of it for drag & drop archiving & most of it for back ups?
the WD drive has shown about 20 MB & I finally ejected the drives to stop it
Also when I look at the WD it shows the start of the backup folder name & it is 2012-12-....inProgress
So it appears to have started from the latest backup & gotten stuck.
The Seagate Drive showed
Capacity 499.78 GB
Available 357.76 GB
Used 142 GB on disk
Another issue is that I tried to open Parallels 5 while this was going on & all I got was the circling circle. I finally after hours forced quit of it since a regular quit didn't work.
& to see what was going on I tried again & after a min or 2, its still circuling so something messed up the memory or something.
So I guess I'll just have to force quit it again & soon shut down for the night & hopefully that will clear out whatever is clogging up the memory.
But I still need to figure out how to do the copy. & whether I can have archived & backup data on the same drive or if it needs to be partitioned. Or maybe that will be different if I upgrade to Mountain Lion? But then i would have to upgrade Parallels or lose use of it.