Just arrived.
To install the receiver, you are going to NEED the .pdf file from the link below. I am going to install a DSM Satellite in the video, but for PPM, PWM, or SBUS receivers you will need to follow the instructions. Note that the link to the FC documentation listed on bangood website is for the Naze32 version of the FC, the Q90 and I believe the 90GT have the F3 flight controller. The installation is a little different, at least for the DSM Satellite.
http://pan.baidu.com/s/1pKuCojh#list/path=%2FMICRO%20F3%206DOF%20%26%2010DOF%20Flight%20Controller