Set the error messages in the same page?

Hi all,
I want you, to see my site register page once…
http://www.rfcables.org/reg.html.
By clicking the register button, with out submitting the details, it will show error message, in another page… because i am checking the details in the another page…
Now i want to show the error messages in the current page only…
how to do this…(not to change more code)

Thanking you…

The easiest way: check the details in the same page.
Otherwise, you’ll have to redirect back to the login page in case of errors.