Good for you! It's such an important skill to have... I have become adept at it but it happened the hard way... I was out... alone and flatted. I had done it once in the garage but it had been a while.
It took me a looooooong time to change that tube, but I got 'er done! Of course, I flatted 8 more times during the next 3 weeks... which made me VERY proficient at changing flats. After the 9th one I went directly to the LBS and bought Gatorskins.
There is a fine line between "hobby" and "mental illness".