Even if you knew how to jack and level the house, this still would not address the CAUSE of the settling problem. It sounds obvious to me that your foundation and piers are substandard and have either settled, shifted, heaved or failed over the years. If you live in a place where it snows then you need poured footings for all piers and walls, probably 3-4 feet deep (depending on local codes). It is likely that your piers and/or walls do not have this and that they have been "heaved" over the years by the freeze/thaw cycles. There are many other causes depending on local conditions. Merely jacking and leveling is not likely to fix the problem and none of these is a DIY project, or even an average contractor project, as most do not have experience or expertise in this area. This is a specialized skill and it is dirty hard work jacking and digging new footings and pouring etc.. It is also very hazardous if you don't know what you are doing. Ever have a house fall on you? It can ruin your whole day!