Solving a Rubik's Cube is usually done layer by layer. Trying to do it face by face would be nigh impossible, as you couldn't do the other faces without screwing up the ones you may have already done.
I will cover three ways of solving the Rubik's Cube: beginner, intermediate and advanced, and I advise you to start with the beginner method. The intermediate method is similar to the beginner, except the last layer is slightly different, allowing for faster times. The advanced method is what is known as the Fridrich method and, with practice, will allow you to achieve times of less than 20 seconds. I myself use a mixture of the intermediate and advanced methods, as I have not yet learnt all of the Fridrich method.
I will try to explain everything in a way where you can understand, as when I first learnt I had to figure stuff out because the tutorial wasn't that good.
The intermediate is very similar to the beginner method. Before you try to learn it, I recommend being very proficient at the beginner method. If I remember correctly, I was achieving times of about 2 minutes before I learnt the intermediate method and, through practice, started to achieve times between a minute and a minute and a half. If you feel that you are really good with the second layer, you might want to try learning a bit of what is known as 'F2L' - First 2 Layers. This is where the corners of the first layer and second layer are done at the same time, saving a a lot of time. F2L will be explained in detail in the F2L section of the Advanced Method.
You can also use some OLL - Orientation of Last Layer - and PLL - Permutation of Last Layer - to aid you in the the steps of this method.
This method starts in exactly the same way as the beginner method - cross, corners, second layer and the cross on the last layer. However, once the cross has been achieved you go on to:
The first step aims to complete the last face, regardless of the position of the cubies, like this:
The first step is to orientate all of the cubies so the last layer is complete. Unfortunately, to do this you have to just learn which algorithms correspond to which combination of the last layer. Fortunately, they're all in this handy-dandy table:
R' U2 R U R' U R
→
→
→
→
F U R U' R' F'
→
→
F R U R' U' F'
→
Make sure that when you do an algorithm you are holding the cube the right way, as you may have to change the way you are holding it in between algorithms.
This step aims to orient the corners in their correct positions, like this:
To do this, you need to find two corners that have opposite colours, like this:
where the indicated sides of the corners are the same colour. Occasionally, all of the opposite sides will be the same colour. In this case, it does not matter which way you hold the cube when performing the algorithm. When doing the algorithm, you hold the cube so the opposite colours are in the same place as indicated in the above picture.
The algorithm is:
x R2 D2 R U R' D2 R U' R (where x means to rotate the cube away from you, i.e. the yellow face is the back face.)
If all of the opposite sides were the same colour before, you will have to repeat this process, as now there is only one opposite pair.
This step aims to orientate the edges of the cross, resulting in a complete cube, like such:
You will either have one or no correct edges to being with. If you have one, hold the correct one away from you, but if you have none it does not matter which way you hold it.
There are two algorithms to use, but they are very similar:
F2 U L R' F2 L' R U F2
F2 U' L R' F2 L' R U' F2
Once this algorithm has been done, you have completed the Rubik's Cube!
CONGRATULATIONS!
