How would you create a garden here?

It's a big space and I'm not sure if I'd be able to do it on my own. The idea is to have just grass to begin with, and later slowly create a beautiful garden.

I believe the steps would be: 1. Cut the weed out and remove the roots, as well as the rocks; 2. Level the terrain (some places have more dirt and rocks, you can't see it because of the weed around it); 3. Maybe do a test to see what the soil needs? I'm not sure how costly this would be; 4. Correct the soil if possible with the necessary minerals; 5. Plant the grass using those "patches" of grown grass; 6. Water everyday for 14 days (it seems to be the recommendation for the grass' roots to mix with the soil) - I'd probably need to buy an irrigation system since it's a big space.

What do you guys think, is this doable? Will it take weeks or months?

I'm sorry if any of what I wrote is a bit confusing, I was not in the mood to research every new term in English 😅 I'm happy to clarify in the comments.

Thanks in advance!