Basically, bombers are very heavy birds. Take 25% fuel, and to as trotter says. Flaps up until takeoff speed, or pretty much when your tailwheel lifts off the ground, then add a notch or two down.
After you get off the ground, stay generically low, but high enough to avoid trees and hills and such. Once you gain a fair amount of speed, start climbing. Don't go too sharp of an angle, though, or you will end up stalling and slamming into the ground, kinda like throwing a penguin into the air
You should eventually get a nice alt (preferably above 15k) and off you go! I'd recommend you constantly check the sky around you for that red nosed devil closing in on you (LA7)
You don't want to get shot down after all that hard work now, do yah?