It's a little funny how there were multiple variations of the whole "do this button combination to make catching easier" thing. The hold down+B was the one I used when I was a kid.
The one other thing I remember believing when I was younger was something about how Jirachi would appear if you beat the Elite 4 100 times. Almost did beat them 100 times too, but when I got close I either got Jirachi legitimately from Colosseum, found out it wasn't true, or both.
After you click respond, then click the pencil icon that should pop up in the lower right of your screen