Cakes are usually cooked on 180, with a fan forced oven you have to reduce the temp to 160 (i think) for about 30-45 mins. If you're making a more dense cake like a mud cake or fruit cake the temp has to be lower, say 150 because they're cooked for longer.

The skewer should come out clean when you put it in. Another trick is to gently push down the top, if it springs back it's cooked, if it leaves an indent it's not. Once the cake starts to pull away from the sides it's cooked. If you put the tin to your ear and can't hear a slight popping noise it's cooked. Um, think I've covered how to tell if a cake is cooked....Usually I just do the skewer test.

My suggestion if you're not a good baker is to make cupcakes and decorate them with coloured butter cream icing.