Thanks to the people who responded so generously. I actually did start replying to the first, but it got too long and it was the middle of the night,so I abandoned the attempt and it disappeared. Luckily I had copied and pasted it into a word file, which I had huge difficulty finding because I didn't know its name so had to teach myself how to find "recent" files. It answers a few of your questions, by no means all.
Here it is. I'll respond later to other questions.
Sorry to be so vague. I have struggled alone since 1982 when a Tandy Radioshack all-in-one computer with a broken disk drive was airfreighted to me in London by an American client. I have always been self-employed so never absorbed the natural mutual learning which I imagine happens with colleagues working in offices. Mostly I did word processing, using a series of WP programs from "superscripsit" through WPD to Word, until the frustrations of Vista (about which I had no warning) drove me into the Apple shop four years ago. I am delighted with my iPhone 4 and my Macbook Air, my second one (hard drive of the first one crashed and could not be saved). But I'm glad this one has two USB ports!. I bought it in about June 2013 and everything is updated to Mavericks.
I don't know how to file my information, since nothing seems to fall into neat categories. I spend hours trying to devise systems which link people to their emails and associations - like a kind of personal wikipedia or private website...
I no longer work for others, having retired and moved to New York. I have many interests and use the macbook for gathering information, organising and recording my life, taking digital pix, communicating with others, etc. I guess it's the last few years with the massive internet growth and universal use of mobile devices, clouds, cable, social media, apps, skype, etc., that has completely overtaken me. I no longer understand what is happening or how it all works. I feel uneasy about the necessity to be always "on-line", and I'm finding it increasingly difficult to interact with badly designed websites (tiny fonts, minute triangles to click), confusing layouts and obscure jargon. I know what I want to do, and have a long list of what I think would be useful, which I could describe separately. I don't like any sentence beginning "all you have to do is ..." or "you just ..." or "it's a piece of cake" especially from anyone who fails to see what is counterintuitive about going to "start" in order to close down.
By the way, I also find TV remote controls, car radios etc difficult, and I don’t think it’s funny that so many other older people share such problems.