Simple music composition on Kubuntu

[Donn]

Hello all,
I have a small tune in my head that I'd like to get out into the air and my 
voice is just about as broken as my old guitar; so I thought I'd look for 
some way to bash it out on Kubuntu.

I have installed Rosegarden, but for the life of me I can't get a sound to 
play; it looks super competent but it's too much for a simpleton like me to 
comprehend -- not knowing the difference between one note and another!

I am googling around, but so far nothing fits the bill: A *simple* way to 
fiddle with notes and times in a hack/test/hack kind of cycle with the aim of 
getting a sound-file out at the end.

I am even looking at Python and ways to code the sound!

Any ideas?

\d