Re: applying a gradient through multiple objects
Press F1 and in the search box at the top type in "Gradient". When the results come up have a look first at "Gradient Panel Overview" as it shows you a 4 colour example have a read. Also with the same search have a look at the second one down "Create or Modify Gradients" as both of these are important to understand. After having a read of both of them go back into your drawing and with the bitmap visible sample each of the colours on Voltron, saving each as a new swatch. With the lettering selected open the Gradient Panel and on the artboard follow the instructions given in "Create Gradients" starting the top and bottom colours of Voltron from the swatches panel. The second bottom colour could be a grey or dark green and here you will need to move the small diamonds on top of the gradient colour line to get the effect that you want. Please come back if you need any more help but I would suggest that you do a tutorial which is not as hard as the one that you have chosen as they are many which cover the gradient topic.
Design is thinking made visual.