How we can GET and POST values


hi all
how we can do get and post value.
i made one form and in this form their is two field loginname and
password.and when i click on submit button than i t should verify from
database and than the next page will arrive .how i can do that.
how i can post value and than get it from that from and check .plese
tell me yhis all in rubyon rails.
hope for reply