Once you have created your Youtube account you can personalise your channel to give it your own personal look or if you are a company you can brand it with your colours and images.
To upload an avatar
Select My channel

Select Settings

Select Choose file

You will then browse and select the image for your avatar in your computer
Once you have upload your image a preview of how you channel will look with your avatar will appear at the bottom of the screen.
You will also be given the option of Remove if you are not happy with it.
If you are happy select Finished Editing

To set a background image
To change the background colour
Select My channel

Select Settings

Select Choose file

Browse to where you background image is. A rough guide is for the background image is 1280 X 800 with the centre panel at 975px leaving you roughly 152px either side of the centre panel. This may vary depending on what the browser settings are.
Once you have uploaded you background image you will be able to view it in preview mode
You will also be given the options:
Remove Scrolling or fixed
and the dropdown menu will give you the options:
No Repeat – Select his option if you have an image to fit the whole of the background
Repeat Horizontally
Repeat Vertically
Repeat Horizontally and Vertically

If you are happy select Finished Editing

Select My channel

Select Settings

Select Choose a colour

Once you are happy with the colour
Select Accept
Select Finished Editing

Your Youtube channel is now customized