Making beer is a 2 stage process. First the wort (unfermented beer) needs to be prepared then yeast is added which ferments and turns the wort into beer.

Wort can be made in 3 ways. From concentrated hopped beer kits, from unhopped malt extract using fresh hops or from malted barley grains. More info on these methods can be found here.

Once the wort has been produced, yeast is added and the fermentation takes place. There are many factors which will effect the time this takes, temperature, amount of sugars which need fermenting (ie strength of the beer) and type of yeast but you can expect most fermentations to be complete between 7 - 14 days.

Once fermentation is complete then the beer is ready to be stored in bottles or barrel and a small amount of sugar is added (known as priming) which will then ferment again but this time the Co2 produced cannot escape and will dissolve in the beer giving the beer a slight carbonation.

Then the beer is left to clear. Again the time this takes will depends on quite a few factors - type of yeast, temperature (cooler the better) and type of container to name a few but you can expect the beer to be clear and ready to drink with a few weeks (4 - 6) and the beer will continue to mature and improve for a few months after this.

All kits come with simple, comprehensive instructions. As long as these are followed and the brewer is careful with sterilisation its easy and simple to make great beer at home.

Once in the bottles or barrel beer should keep for many months and in fact many beers will benefit from some extended maturing.

Flat beer will either be caused by too little priming sugar being added to the bottle/barrel or the sugar has not been able to ferment due to temperature.

If the beer is in a barrel then it could be that you have a leak from the cap. Trying adding some co2 and see if this works, if there is still no pressure then check for leaks around the cap.