If you actually want to do it yourself and build a wood deck, then read at least a number of of the provided DIY decking directions. Grab pencil, paper, and ruler and plan your garden development as good as you can. Draw a view looking downward on the timber deck (plan view) and draw an additional view looking at the deck from the frontage (elevation). Draw the knock down to level and it will give you a thought of what it will appear like later. Draw a diagram of the joist and carrier arrangement below the decking boards and you will be able to decide the quantity and sizes of timber you need and approximation the price. And of course make sure you get all the relevant power permits and approvals. Take your time and take pleasure in doing amazing for yourself.