One thing that will help you remember the part about low/high water concentration is that you should try not to remember it! Every time you need to write down what osmosis is, work it out, then write it down, and you will never get it the wrong way round. The direction the water goes through the membrane will always result in the different water concentrations on either side of the membrane equalising, rather than becoming more different. I don't have any web sites to offer other than the excellent one found by Fern57, but this is basically the most important fact about osmosis that always appears on the exam. Once that's sorted, the rest is easy.