Bulb Replacement

How diffucult is it to replace a bulb in a front headlamp?

My wife and I recently bought a car from some friwnds of ours. The driver-side front headlamp has blown. I bought a replacement bulb for it and attempted to replace it myself, but access to the back side of the headlamp is limited. I may have to disconnect the battery to gain access and remomve a plastic cover that appears to be glued onto the frame. Because of the type of car I'm working on would disconnecting the battery and moving it out of the way be the right step.