One thing you need to decide is if you are a geometric type of person (straight lines, rectangles etc) or an organic type of person (circles, curves etc). Then depending on what you are, sit down with your plan and tracing paper with either a ruler or protractor & a set of French curves (or flexible line) and draw out your garden. Mark out the patio first and be generous with it, then mark out any paths you need to a shed or washing line, then insert your lawn and borders. There are lots of good cheap books on garden designs for small gardens. Invest in the time now and reap the rewards in the years to come.
Is it just me or are these comments from fellow gardeners unreasonably negative and critical? This person is asking for our help and ideas....of course, the books say plan your garden before you plant anything etc. etc. but if you're a mad keen gardener then it's hard to be patient. I say go for it; plant where you think they will do best (consult online etc. where you can) and you can always move them. That's the great thing about a garden; it is probably the most flexible, creative blank canvas out there. Make a mistake...well just dig up the plant and try again. Good luck with your garden and enjoy it.
I'm confused now. The photos show two separate square looking slabs of terrace but your yellow line is long and narrow.Instead of drawing it on the PC, try drawing it on paper to scale as I have suggested and then take a picture to post on here.As for circles and curves, get out the tracing paper and some string or a protactor, cups, glasses, whatever to draw curves and circles. You can also use a hose-pipe laid out on teh ground and then look at the shapes form all angles, including upstairs windows, to see that it pleases or still needs tweaking.Last thing to establish is ownership of that wall. If it's yours, you can happily drill into it to attach fixings for trellis panels or tensioned wires for growing climbers which can be fruiting or just ornamental roses/clematis/honeysuckle/wisteria..... If not, you'll have ask permission or erect posts in front of it to carry wires or trellis panels.
One thing you need to decide is if you are a geometric type of person (straight lines, rectangles etc) or an organic type of person (circles, curves etc).