how do i get them??

you attack them and beat the force that are on them
they are just as regular op's except you can't attack from metal and oil well, and relics can move

What if an ally is there and i send my squad there?

If by ally u mean someone in your alliance, then your troops just move there and no ownership is changed.

If by ally you mean another alliance that you are allied with, then your troops are attacking it and will change ownership to you if you win. But your ally will certainly not like that and will probably declare war on you