There are many methods to attempt the update you desire, and it certainly should be possible on a 9860 (I myself used to have one on 7.1). So, please tell us what you tried...from "not able to update", there is really nothing we can deduce...
Do, however, keep in mind that while 7.1 includes the capability for HotSpot, the service itself must be allowed for and enabled by your mobile service provider -- if they forbid it, then it will do you no good anyway. Some carriers freely allow it; other carriers totally forbid it; still others allow it, but require extra fee from you. So you will need to check with them to be sure.
Thanks and let us know!
Occam's Razor nearly always applies when troubleshooting technology issues!
If anyone has been helpful to you, please show your appreciation by clicking the button inside of their post. Please click here and read, along with the threads to which it links, for helpful information to guide you as you proceed. I always recommend that you treat your BlackBerry like any other computing device, including using a regular backup schedule...click here for an article with instructions.