So your alt text should succinctly describe the contents of your image. A helpful rule of thumb is to write the alt text as if it were to be used as a caption for the image, so it should sound natural and be descriptive.
Kitabu chao cha wenye kudhani wanauwezo kinageuka juu chini nikiweka kitandanai kwangu,ishara ya juu chini ni ishara ya kuonyesha nisiamini mambo wanayonifunza na nianze kufuata na kufanya mambo yangu.