È abbastanza facile tradurre "I learned to play the piano." = "Ho imparato a suonare il piano."
In oltre "I was learning to play the piano." = "Imparavo a suonare il piano."
Però come tradurre "Since I'm between jobs, I have been learning to play the piano."
Forse si usa "sono stato imparando"? "ero imparando"?
And now to spare all of you the trouble of slogging through my Italian, I'll explain my question a little better in English in light of the answer by abarisone. I frequently find myself trying to express the idea that I am currently doing something that I began in the past, but have been working on for a substantial but inexact amount of time, with the intent of implying that I have accomplished a decent amount of it. It is common (in Northeast Corridor American English anyway) to say something like
"I've been making pasta for the party."
This carries the implication that I have already made a considerable amount of pasta. On the other hand if I were to say
"I am making pasta for the party."
I might mean that I just began making pasta and I haven't yet made any, or I might mean that I have a huge pile of pasta already made since I started the process.
My guess is that in Italian, if I want to express that I have already made a substantial amount of pasta, I would simply say so rather than trying to imply it through verb tense/mood.