Fuel Injection - explain this to me like I am 6 years old

Throw a bit of timing at it, then start leaning it out.
The "book" says the timing should be a TDC. I have mine set at 10° BTDC because it seems to run so much better. Plus I seem to remember someone on FABO recommending going to 10 BTDC, and I liked it.
I think the idle vacuum was at about 15 at 650-700.
I have done some more tuning and leaning it out. I just need to get it on the road to figure out the mpg.

I truly do appreciate the information. But I am a retired electrical engineer and have not worked on a car (on even paid attention to the workings of the cars) for about 45 years. I think that would be about 1973.
That is why I titled this explain this to me like a 6 year old