Garden DIY SOS Help needed decking, paving,

Please give any advice. Hve removed a greenhouse and have an old concrete path running from steps up the garden to old greenhouse area, the path has a small wall that has a raised lawn. Ideally want decking in the old greenhouse area, how much should we be looking to pay for that? can we use the old brick wall thats there already or should we remove that?

looking for easy/simple solutions for path and small wall.

thank you

Loads of pictures, but not much info to go on.

What's the size of the deck area you wish to cover?
Will it be raised decking or flat onto the concrete plate with a frame?
Any steps or handrails required?