A flying wing turns the same way a more conventional aircraft turns. The wing is banked and for a level (or climbing) turn its angle of attack is increased, using whatever control passes for an elevator. There isn’t much information publicly available regarding the control system of the B-2 bomber, but it’s probably safe to assume that it is computer controlled and doesn’t necessarily depend on aerodynamic surfaces for stability. From the pictures it appears that the things that looks like split ailerons provide yaw control (the equivalent of a rudder). The flap like things near the rear of the wing are the angle of attack control (the equivalent of an elevator).

To fly a turn, the roll control is used to bank the wing, and the yaw damper (or computer) uses the yaw control to eliminate any adverse yaw. Simultaneously the pitch control increases the angle of attack enough to maintain level flight.