Quick answer: tar czf .
a bit longer:
c - create archive
z - gzip compression
f - filename
You don't need z if you don't want it compressed. Using x (extract archive) instead of c does the opposite when you want your files back.
I don't know, but I'm sure it's also possible to either use wildcards or just type the list of files you want to have tarred instead of , if you prefer.
Sincerely,
-Kenneth Straarup.
EDIT: the flags can come in any order, btw, cfz fzc, etc, afaik. It may depend on tar implementation, though.
