Well, the extract option is -x, and since it's gzipped, you'll need -z, so
tar -zxf cst-0220404.tgz
A lot of people always use -v (verbose) which IMO is stupid. Writing to the terminal is a couple of orders of magnitude slower than writing to a hard drive, so all -v does is slow the process down substantially. If you want to see what's in the file, then look at it with less, assuming you have a working lesspipe.sh, if not, then use the -t option:
tar -ztf cst-0220404.tgz | less
All this, and a lot more, is documented in the man page, which should generally be your first point of call for questions like this, though some man pages are better than others. GNU tar, like most gnu programs, also has an info manual, which is more complete than the man page.