We recommend the version from AdaFruit that already has the appropriate configuration for the PiTFT screen, see https://learn.adafruit.com/adafruit-pitft-3-dot-5-touch-screen-for-raspberry-pi and follow the instructions.
The first time you power on the Raspberry Pi after flashing with Raspbian, you will need to perform the first-time bootup configuration. Here's what I recommend.
The Raspberry Pi should be plugged into a live internet connection via its ethernet port. Then, log into the Raspberry Pi, either by plugging in a USB keyboard (and using the on-board PiTFT screen) or by using SSH (Secure Shell) from another computer on the network. Note that if the Raspberry Pi was plugged into the network (and assigned an IP address via DHCP), the message “My IP address is …” and then the obtained IP address should appear on the PiTFT screen, just above the login prompt.
The default username is “pi” and the default password is “raspberry”. We recommend running the following:
If you connect anything to the serial port on the GPIO pins (as you would if you were connecting an OpenCM 9.04 board, for instance) you'll need to reconfigure the Raspberry Pi as it usually runs a console on the serial port (ttyAMA0).
dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait fbcon=map:10 fbcon=font:VGA8x8
, change it to say
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait fbcon=map:10 fbcon=font:VGA8x8