As others said, you need a new motherboard, ddr4 ram and to reinstall windows. If you don't have an aftermarket cpu cooler you'll need one of those for the i5 6600k as well. The k series cpu's don't come with a stock cooler, just the chip.
2nd/3rd gen intel cpu's used lga1155.
4th/5th gen used lga1150.
6th/7th gen use socket lga1151.
The socket has to match the cpu model/generation or it won't work. A z series motherboard will be needed to take advantage of the unlocked properties of a k series cpu for overclocking, otherwise consider a locked non k cpu and an h or b series board like an i5 6500 with an h110, h170, b150 etc. An i5 6500 or 6600 come with a stock cooler. The 6600K does not.