Designing and Creating a New Garden with Water Feature

I'm starting with an empty area about 10 x 4 metres between sun lounge and observatory in front of living room window and facing roughly south.  I have killed off most of the weeds and grass by covering with an old tarpaulin for a year or so.  This has also stopped the ground from drying out and making it easier to dig.   In addition to providing a path to the observatory, this will provide flowers and shrubs to see from the living room window.  Plus a small pond and fountain.  The latter is something I have been working on in 3D printing and plan to have something unique.  Apart from the pond there will be planting areas and slabs and ornamental stepping stones.