How do you use cheats on the computer game spore for the computer

Hold CTRL-Shift-C all at once, and release.
A console should appear, then type in whatever cheat you want, e.g addDNA and hit Enter.

http://www.sporecheats.com/
^ Got a huge list of cheats, and explains each in detail.

Enjoy!
and do not hesitate to ask more questions if you get any problems.