OTA
Get yourself on a Mass & Balance course, it's the only way to learn the ins and outs of manual load-sheets. This from a guy who used to teach M&B professionally for a number of years.
As a previous poster said, picking up bits of information on a message board will leave rather large holes in your knowledge. Furthermore, there are a number of different load-sheet lay-outs and philosophies, and while they all effectively do the same thing, there are different ways you get to the end result depending on the lay-out and philosophy of any given load-sheet, i.e. is the trimming done by whizz-wheel, drop-down box, christmas tree or index numbers?
As for weights and indicies, that's relatively simple - but won't teach you how to do a load-sheet: Furthermore, the terms used differ from airline to airline, just to make things a tad more complicated. But here's a short rundown:
DOW - Dry Operating Weight (Same as OEW) = Aircraft + crew and standard items (catering, oil, ships documents, catering etc)
DOI - Dry Operating Index = Centre of Gravity at DOW
OW - Operating Weight = DOW + Take-off Fuel
ZFW - Zero Fuel Weight = DOW + payload
LIZFW - Loaded Index ZFW = Centre of Gravity at ZFW, can be translated into a MAC%
RAW - Ramp Weight = ZFW + Ramp Fuel
TOW - Take-off Weight = RAW - taxi fuel
LITOW - Loaded Index TOW = Centre of Gravity at TOW, can be translated into a MAC%
LAW - Landing Weight = TOW - trip fuel
LILAW - Loaded Index LAW = Centre of Gravity at LAW, can be translated into a MAC%