I had a few issues while making my phone (which is a Nokia Lumia 800) into a hot-spot, and I’ll note some steps here, hoping to help someone with the same need.
I think this also applies to the Nokia Lumia 710 unless one of you says otherwise.

For tethering, one needs to use Internet Sharing, which can be found under Bluetooth in the Settings of the phone (application with the gear icon).
I hear this process is much simpler on Android.

First of all, the Lumia 710 and 800 did not not come with the Internet Sharing feature by default ( it might, in the newer phones). I had to use Zune, and under Settings (in the top), I had to select “Phone” and then “Update”.
This is also known as the Tango update.

After a bunch of steps, that included downloading the software, etc, I saw the “Internet Sharing” option in Settings.
To set this up, one has to add an APN for the network. This is done by selecting the “Network Setup” app on the phone and adding a name, and simply adding “internet” in the Internet APN setup section.

FYI, there is a website with a number of APN settings for various phones and operators worldwide).
Add a proxy if you’re using one, or just leave it blank.
I am not sure if you also have to set up the APN screen (in the Cellular section), like above too.

Power down the phone (by holding down the Power button and sliding down the Lock screen and to power on, hold the Power button again) – this is important.

Once this was done, I turned the Internet Sharing ON and was able to browse the net.
Hope this helps you…