Need Help setting up my mash tun profile for BIAB and for all grain.

Im totally lost on how to do this.  I have 2 kegs 15.5 gal one is typical AB keg the other is an oversize 15.5 keg not sure what kind.  Ive attempted to set up my profile by using the ss keg set up and modified it for BIAB for 10 gal batch and 5.5 gal batch. I would like to use the oversize one based on a wider middle for my BIAB keggle.  I did only a 5.5 batch size however, numbers didnt add up and suggested to me that i needed to add water.  Im totally lost on how to do this.  I did a search on this website and honestly was very difficult to have replies on similar questions.  Either im doing something wrong or there is no one answering to peoples post. 

Thanks!1

Check the tutorials at    http://beersmith.com/support/    and the posts at    http://www.beersmith.com/forum/index.php/board,21.0.html      Somewhere in there is an excellent extended discussion of how to set up your equipment profile.

The most critical part of your Beersmith setup is estimating (then refining) your equipment profile. First you estimate your losses to grain absorption, dead space (the volume of wort you're unable to drain out of the mash tun), wort you're unable to drain out of the boil kettle, wort left in a chiller, and thermal contraction (water contracts as it cools from boiling to pitching temperature). You can get a good estimate of most of these by running water through your equipment. After a few brew sessions you'll be able to predict the losses very accurately.

I've been delighted with the accuracy of Beersmith since I dialed in my losses.

Here's a link to an extended discussion of equipment profile set up.
http://www.beersmith.com/forum/index.php/topic,5140.0.html

Sorry for the delay but THANK YOU!