How do I use the Image tab?

[generone24]

Sent image from gallery to Image tab
Changed the prompt and the seed.

Sent image to Sketch subtab.
Drew on sections that I wanted to replace.
Clicked generate, nothing changes except for the fact that now the drawing I added is directly in the image.

Sent original image to Inpaint tab instead.
Drew on sections that I wanted to replace.
Inpaint mode: masked, Inpaint area: full
Clicked generate, literally nothing changes, the input and output images are identical

Finally send original image to Composite tab as last resort.
Drew on sections that I wanted to replace.
Inpaint mode: masked, Inpaint area: full
Clicked generate, same result as when I used Sketch.

What am I supposed to be doing?