The differences between soluble fibre and insoluble fibre are...
Soluble fibre becomes sticky when it combines with water and forms a gel-like substance in the intestines, examples of insluble fibre foods are found in fruits, veggies, seeds, brown rice, barley, oats and oatbran.
Insoluble fibre acts as a sponge as it passes through the digestive tract and absorbs moisture many times it's weight in water. By doing so it increases the bulk of stools AND softens it. These characterisitics facilitate the transit of foods through the intestines and prevents constipation, insoluble fibre is found mainly in wholegrains, legumes (beans, peas and lentils), and the skins of many fruits and veggies.
My sister eats oatmeal everyday in order to keep her IBS under control, for many it's as simple as that.
I take fibre supplements and eat plenty of fibre...when I first started taking the supplements it cause me extra bloating and gas, which is normal even for healthy people it's just your system adjusting, so you should always add fibre slowly and with supplements drink plenty of water with them.