https://www.raspberrypi.org/blog/the-eagerly-awaited-raspberry-pi-display/ i bought the above products, but don't know how to configure screen touch keyboard? and raspbian is the OS, is it the only OS available, since it said installing it will delete all other OSes on SD card, but it should only that in the menu.
looking at the product pictures for the touchscreen it needs to be plugged into the display port on the Pi with a ribbon cable as shown. You then need to connect the appropriate GPIO cables. Next enter these commands into the LXTerminal:
sudo apt-get update sudo apt-get upgrade sudo apt-get dist-upgrade sudo apt-get install raspberrypi-ui-mods sudo apt-get install raspberrypi-net-mods
When you power up the Pi the touchscreen should work. See this guide for more information.