It's not too hard, just spawn in a free flight mission and follow the guides here.
After a couple of offline trial runs you can also go online on ATAG and ask specific questions on their teamspeak. There is a cadre of more or less bomber-specialized pilots there across various timezones and they are all willing to help: Jimbop and Dutch are usually handling the Blenheim, Keller is instructing people on the 111.
I'm also joining them every now and then, but i usually join late and my mic remains unused (don't want to wake up everyone in the house at 5am, shouting "bombs away!" hahahaha
), but i listen in on TS and will reply on the in-game team chat.
Generally speaking, after some collective effort there's enough knowledge to use bombers and enough people willing to "teach" it to others. It won't be an exaggeration to say that when the next patch comes, at least online play will be significantly transformed. Bomber pilots are already winning maps with bugged bombsights and despite the memory leak bug. This last one prevents people from flying in groups or with escorts and forces bombers to go in alone, in staggered runs with an advancing fighter sweep or low on the deck. And still, maps are consistently won and some people can close a target in a single run.
Imagine what happens when we can fly in groups, with escorts and debugged bombsights
