How can I transform this backyard space (picture)?

Here’s what I do, take pictures like you did of these two areas, then use the edit mode of three dots... and it gives you a few colors and implements. Then draw on your photos, use Pintrest for S. CA. Landscaping for ideas of plants ... here’s some samples I did on your photos. I drew a simple deck around tree, for a bistro set. A bench in front of hill, maybe a bird of paradise in far right corner? River rock and mulch from deck to fence, with pretty grass, lavender placed among it. Far left corner another largish shade/ partial shade flowering plant. You need color, try to find a fountain that’s colorful, like these pot fountains but even more color in them. The centered fountain has those pebbles and concrete around them, but you could use flat stones, DIY stepping stones. And you can use stones to radiat away from the fountain and in between maybe the lavender?

I would build seating around the tree (leaving enough room of course for growth). Perhaps a pergola for shade and another seating area. Amazon has some nice shading cloth that you could put over the top of the pergola in the spring and take down for storage in the fall.

I would rip out all shrubs and go with more of Japanese maples in the shady spots, with adding a decking around the tree an scale the left side of the yard add large birch trees surrounding the fence line so it won't take long to shade... Then you can place patches of grass through the yard but its split up by setting the yard up.. It would be costly but you can add a pallet couch around the tree and on the other side of the deck you have a brick bbq depends how much you have to spend,lol

Oh no, do not use any pallet lumber for your new yard.

If you are going to invest money, time, and effort into transforming your yard, put longevity, durability, and low maintenance as priorities. Use only exterior recommended building and landscaping materials.

Thank you

Garden container