UNIX newbie question

[joko@crl.com (Joe Kohn)]

I know next to nothing about UNIX, but I finally found a reason to learn
how to compile a program. The other day, a few folks on IRC told me about a
Unix Jpeg to GIF converter that is located at wuarchive.wustl.edu and can
be found as /multimedia/jpeg/programs/jpeg4src.tar.Z

I wrote to my system administrator and he said he'll put it on his to-do
list. Or, if I wanted to compile it myself, I could.

The brief instructions provided me:

"ftp download the archive...

unpack it with:  zcat jpeg4src.tar.Z | tar xvf -

It should make a subdirectory, 'cd' into that directory.

Try a 'nice make'. If that fails, look for a README or INSTALL file and
follow the instructions there.   If that fails, the program may need some
porting work (SunOS, the Unix we're running, is pretty standard, so this
should not be a problem)."

A couple of questions...

1) Is that really all it takes to compile a program?
2) If I can successfully compile the jpeg to gif converter, how do I run
   it?
3) What on earth is a "nice make"?

Thanks in advance.

Joe Kohn