How to correctly eject a ScanDisk.

I have a MacBook Pro with OS 10.6.8. My new digital camera does not have a cord to commect it to the laptop, so I inserted the SanDisk to download the new photos. When I was finished, I pulled the disc out. I got a message on the screen that I had not properly ejected the disc and may have compromised the contents.

Question:

How do you properly eject an SDHC Card? I can't find the info in iPhoto help.