How easy to create new major mode?

["Tim Morley \(remove vegetable for email address\)" <tim@teamlog.turnip.com>]

Hi all.

I believe the solution to my current emacs challenge will be to create a new
major mode, albeit a very simple one. I'd be grateful for
   (a) confirmation that this is the way to attack the problem (or failing
that, a better suggestion)
and assuming this is indeed the case
   (b) guidance/URLs/code samples to help me put together what I need.

What I would like to achieve is a customised system of syntax colouration,
to help with reading through hundreds of lines of text. All I need is for
lines starting with the word User to come up in, say, magenta, and lines
starting with System in blue, with a default text colour of grey. (There are
carriage-returns at the end of each line of text, so my keywords will always
be at the beginning of a new line).

I've had a look at the .el files for the various existing modes, but as an
absolute novice in Lisp, I'm not sure which are the relevant bits to
cut-out-and-keep.

Any pointers will be very gratefully received. Cheers all.


Tim Morley