I got a mid-length 16" barrel from RRA, but I do not know how to take off the handguards and barrel that are already on from my gun.  I can't add the new barrel without finding out. Here is essentially my gun (the top picture, 20")

http://www.rockriverarms.com/item-detail.cfm?ID=AR1500X&storeid=1ℑ=va407.gif&CFID=35446326&CFTOKEN=34531629

I don't know how to make it hot, so please just highlight click copy and copy it in web address bar.

What part of the state are you in?
ETA:  If you are wanting to do this yourself you are going to need some tools and a download of the -23&P from the manual download section in the Information board.www.ar15.com/content/manuals/
You want TM 9-1005-319-23.
You will also want to look at TM 9-1005-319-10, which is the Op manual.

Dallas Texas, but I have ranch in-between Throckmorton and Breckinridge that I got to every weekend.

There's a lot of us in the DFW area.  I do sideline work on ARs for a shop in Waxahachie.  D-Ray's in Dallas does some gunsmithing, I don't know what they would charge to rebarrel your AR.  I think there are some places in FtW that will do it.  Gunmaster in Plano as well.
To do it yourself you are going to need a receiver block, barrel wrench, torque wrench, and a breaker bar.  Some other small tools will be needed as well, such as small punches, a rubber/brass mallet, and possibly some pliers.
When I get a chance to look at my TM I'll tell you what section to read.

Does D-rays have a website?