have to do do a nat traslation to a group of address have try alot of ways none seem to work right suggestions
also does any one know the reqmended eterior to interior address ratio??
First, you can just use the masquerade action of the nat group.
/ip firewall nat add chain=srcnat action=masquerade src-address=w.x.y.z/a
You could also use the netmap (this does a one-to-one mapping), or same (this makes sure that the same addresses from a pool of addresses are always given out the same. You can look up the different ways here:
http://www.mikrotik.com/docs/ros/2.8/howto/howto.content#12.2.3 → how to make an home router with a dsl connection
http://www.mikrotik.com/docs/ros/2.8/howto/howto.content#12.2.6 → how to make internal lan addresses visible to the wan.
Finally, here is the nat section of the manual.
http://www.mikrotik.com/docs/ros/2.9/ip/nat
Oh, and I am assuming you are using 2.9.x 
Hope that helps
I not only have adreess inside but i want to use a NAT pool for the users a group of outside addressses any idea how to do that
??