Here is a nice video that walks you through the process of binding your FRsky X8R receiver to your Taranis X9D radio.
Overall its quite simple, if you wish to bind it in another mode you just need to refer to the table below and place the jumper between the required channel. Also be sure to set your taranis to the corresponding mode. In the video above the X8R receiver is set to mode 5 as it does not require a jumper. However for most users this mode would be the best mode to use as it enables 8 channels via PWM which is plenty and still allows for the use of telemetry.
Once you have bound your receiver to the radio you will also need to setup the channels and switches on the mixing menu. Please refer to the Taranis X9D manual for more information.