use tile effect to create a block of identical photos?

hello,

I want to take a photo (bitmap) and create several rows and columns of the same picture with no space or gap between pictures and minimal or no overlap either.  tried to figure out tile from the help but it is not clearly written.

any good tutorials on how to do this?

currently I am using duplicate function to line up images but they are a pain to line up exactly in large numbers.

thanks!

Msongs