Change the Language Manualy

Good evening, my question is what files are for me to change the language manualy in the registration form, for some odd reason i downloaded the spanish file and was able to change and have the option for spanish castillan. But some things where not fully translated examle *the registration form, Blog Roll, Log in, Calender *los meses estan en ingles*, lost your password, and a few things in the wp-admin. If you can help me identify the files i can manualy edit them to spanish i use Dreamwaver.