how to fetch and show the results randomly with/without loop php

hello all i am having a site where i need to show random users/ members in this format

i want images of the user in the format as above randomely i have more than 9000 members and need to show the random users in this format the design repeat itself by three

i dont know how to use the loop or use the query to show the images in the above format.

my query is like

  select image,id,somethingelse from tablename where id !='' order by rand() limit 21 
 // i want 21 images to show here 7*3 (the image here repets it self by three)

please give me some hints or any llink i am stuck over here .....

numbering of the image can be changed ....