[texhax] subfigures

[M.N.A.Smadi]

hi;

I have 4 figures that i want to label as x.a and x.b 
and y.a and y.b   (where x and y are the numbers that tex assigns). I 
think that is called subfigures, How can i do that?

Also, how can i force tex to show x.a and x.b on the same page without 
anyt other contents in the page?

thanks
m.smadi