how to replace spark plug for buick regal

Just like any other car. You need ratchet wrench, a 10 inch or longer extension and 9/16 or 5/8 socket. You may need to lay on top of the engine to do it. Not hard just difficult unless you are agile.

Well for starters some more info would be nice. Like Rear wheel drive style?Front wheel drive? Motor size?

Do it with cold engine, but you require a complete socket set that has at least 3 extensions, angled short extension, etc, all in three eight drive, otherwise its diffilcult.