1. Upgrade the firmware to the target version which support wifi hotspot fuction.You can refer to the following FAQ to step this.
How to use SD card upgrade MDVR for JS2-HD series
MDVR firmware upgrade using USB
Offline Upgrade Instruction
How to upgrade firmware using IVMS Client
2. Go to the wifi SET UP page and config the parameters you need use.
How to set wifi parameter to support wifi hotspot function.doc