Remove the front about 12 clips be careful not to snap the clips easy to do. More when fitting it back on.
then you have to remove the inner black section, again done with clips like the clear section.
then last part to remove the inner base I'll call it :)
Should now look like this
So now I used cotton buds for cleaning your ears but you might find something else works better. But in the picture it's already been removed but it will look a black and green colour and under that is a green filter stuff. Both the black and the green filter is removed with the ear buds and nail varnish remover. But once removed should look like below. you will need to do that too all the sections of the speedometer. you can slightly see where I haven't removed all the green filter.
Then you can put it all back together again and remove the old bulbs to replace with the new colour bulbs you have chosen. End result should be.