Vedic Kings.....Heya, there is a program that you can download that lets you edit HDRI images. The program is called "HDRI Shop" and here is the link to that....
https://www.ict.usc.edu/graphics/HDRShop/

As for using a HDRI image in Maya, just insert the HDRI image into the Image Based Lighting option in your Mray Options.

Hope it helps

Alienscience.......Howdy, yeah I am, we are doing a few projects for a few clients at the moment, this house is being made just to add to our portfolio, you can never have too much work to show..hehe.. Cheers