Default [Q] install ROM on LG E400 without ROM manager

I wipe all data and system in CWM. Now I want to install ROM CM, but I can't launch CWM. Is it possible that I erase CWM to?
How can I install the ROM?
I've got LG E400 (Optimus L3). Just notice I have had already the CM 9 on my phone.
Thank you a lot,