Hello and welcome to the forums!

Do you mean free wifi hotspot? Because if all you want to do is connect to wifi with your phone you can already do that for free just by going into your WIFI settings and connecting to it.

If you want free wifi hotspot (IE using your phone as a wireless router), then your going to have to root your phone and the best thing to do is flash a ROM with the sprint hotspot hacked so that it works for free..

Information for how to root can be found here:
http://androidforums.com/evo-4g-all...-rooting-gingerbread-2-3-5-dummies-guide.html