Annoying newbie question :-)

["Ross Archer" <dogbert@mindless.com>]

Hi Apple ][ enthusiasts!

I have a "new" Apple IIc I found very cheap. It starts up, and
thanks to what I could glean from the huge Tech reference book that
came with it  (complete with schematics and a full I/O map!),
I was able to launch the mini-assembler and write a few routines,
and go into BASIC and write a couple of little programs.
Great. I can hack characters on the screen and make the speaker tick..

So now what?  I'd like to save my work to diskette.  I can't find out how
to do that.  These sorts of questions are apparently far too basic
for the Tech Ref. manual, and so I'm clueless as to what I need.
Do I need to boot ProDOS or some sort of OS disk just
to save my work?  If not, what is/are the command(s)?

If so, how would one go about locating a copy of ProDOS
suitable for a memory-expansion (late-model) Apple ][c?

Thanks for any clues, pointers, etc.!