I have a LG En-V 9900 and its on metro PCS line. I want to put ringtones on it but i dont know how to! Plz hlp?

Ok so my mom took my LG En-V to the metro pcs store and they flahsed it so now its on the Metro PCS lines insted of the verzion ones. My prombelm is that i want to put ringtones on my En-V but i dont know how to. I tried to downloading store on the phone but nothing. Pls help! :) thanks!