would be hard to jack anything up.. unless you put your rear wheel back on crooked.... the front sprocket is one nut and I do believe there is a thread on it cause I had asked a while back about how much torque the front sprocket called for. the rear one is common sense , just take your wheel off remove sprocket and replace with new one..and tighten down the bolts in a cross pattern like a car rim or anything else.
It is extremely simply. I will look for the thread onthe front sprocket for you and let you know if i find it.
you state simple but is there not a issue of the correct way the sprocket goes on, like it can be place on back to front can it not..also btw for help check out youtube, heaps of movies that show the" right" way such as undoing each bolt in "sync" like loosen/tighten each opposite one etc..