Hello,
Here is a link to the administration guide of the device:
http://www.cisco.com/c/dam/en/us/td/docs/routers/csbr/wrv200/administration/guide/WRV200_V10_UG_A-Web.pdf
On page 28 it shows the steps to upgrade the firmware.
In short you will need to log into the device, go to Administration - Firmware Upgrade, then click on Browse and select the firmware file.
By the way, the firmware file should have an .img extension. If I'm not mistaken, the last firmware released for that device was the 1.0.39
In general upgrading the firmware is always recommended to increase reliability and performance.
Please let us know if you have any more questions. Also, don't forget to mark an answer as correct if it was helpful to you so that others can benefit from it.