Forwarding from your Inbox:
There is two ways to action this functionality. In your inbox, swipe to the left on the desired message you are needing to forward. The forward option will then populate, from there you will select the user or group you need to forward the message to.
Forwarding from Within a Thread:
If you are in the message and have read it but, need to forward it you can hit the three dots in the upper right hand corner. From there a series of options will populate but, please select Forward Thread. From there you will select the user or group you need to forward the message to.