Then you need to feel that there is enough of your app complete to be worth testing. For instance, I don't really-truly care about whether the home screen looks right, if all I can do is look at it. I want to know whether it works when I press buttons.
Then you Save All (Ctrl+Shift+S), and finally you go to the green and white Button for "Run Wedding Logistics".
Having already specified a test machine (in my case using the specs for my own Android phone), it should just load up. Be aware though, this step can be veeeery slow.
And...ah. Oh dear:
Well, at least you can see what Toast looks like! As well, of course, as the appearance of the testing software [which is included in Eclipse].
It does occur to me that most programming I've done will talk about de-bugging, and this seemed to be more of a 'run program' option. Hmmm. *Looks around* Aha!
I clicked on this:
I should have gone for this:
The Debug button. Debugging is one of those terms that is more literal than you think - while the origins are obscure, it was popularised in the days of the first computers, vast buildings full of valves such as Colossus or ENIAC. - when it was possible for a bug like a moth to get into the works and cause the machine to behave in unexpected ways. The archetypal bug is pictured here.
I believe my error is linked to the fact that the tutorials from hackaday were with already completed and tested code - so the bit of seeing it work at the end was just the reward. Anyway, now I hit Debug, so I'll see what pops out:
Source not found.
Ah. I have no idea. Will have to come back to this once I've done some more reading.