Although the above node is excellent, there exists an even easier ways to get good brews.
Most brewshops, and I have noticed even the supermarkets, now have cans of wort. The most common one is 'Coppers', but any brand will do. The only difference is they will have slightly different tastes. To this ready made wort the minimum that is required from you is to add water and sugar, and away you go.
They make 20-25L from one can, and the ability to vary the recipe is very easy: substitute dextrose, malt, or barley for plain sugar, add extra hops, or change the yeast. Decreasing the water content will get a slightly higher alcohol ratio, and a stronger taste. Increasing the water content will weaken both.
In a 30 litre fermenter add, 2 litres hot (boiling) water.
Into this add can of wort - it is always a good idea to have had this soaking in hot water for 15-20 minutes to get all of it out!
Add either Sugar, Dextrose, Malt, extra hops. (you can even add herbs here!)
I am assuming you have followed all cleaning and sterilizing tips in the above WU!!
Add clean cold water to bring the total up to 20-25 litres (again your choice)
Add yeast - Some people suggest 'pitching' the yeast, which is tipping it into a glass of water before you start, with half a teaspoon of sugar. This get the yeast 'going' and speeds fermentation. I do this because I like to watch it foam up and bubble and it makes more of a mess for the flatmate to get angry about. It isn't necessary, just sprinkle the yeast into the fermenter straight from the packet.
Put the lid on tight, with vapor lock in place (have water in it!)
kick back and enjoy doing nothing for 7-12 days!
It truly is that easy!