there's a write-protected tab on either the left / right side of card that has a slider (like the old floppy style); just move that away from the direction that indicates "locked".. its usually a yellow or white-colored tab that can be moved.
for best reference i can find of a detailed photo.
Hope this helps
A+ Core Hardware, Software Certified (May 13 2005)
the new beast...
AMD Athlon XP 3200+ Barton running at 2.16 Ghz.
GeForce MX 4000 (mainly takes the load off the main system)
Creative Labs Audigy 24-bit sound.
Some Case from tigerdirect
512 MB Ultra DDR RAM.
80GB Seagate HDD
LiteOn CD-RW / DVD ROM drive.
currently looking at a litescribe drive at staples, due to its ability to label the CD shortly after being burned.