“Toon Larner” is a set of resources from North Tyneside Brass in Schools to help you learn to play a brass musical instrument.
“Toon” in this context translates as “Tune”, and “Larner” as “Learner”, so it means “Learning (to play) Tunes”.
But “Toon” is also the local name for the City of Newcastle upon Tyne as in “I’m gannin’ doon the toon” meaning “I’m going to town”, probably shopping, or for a night out.
And “Toon” is also used for the famous Newcastle United football club as in “De ye think the Toon’ll beat the Makems temorra?” meaning “Do you think Newcastle will beat Sunderland tomorrow?”