[SOLVED] Error Message in newthread form

[omardealo]

Hello ...

I add new filed in newthread form , this field will contain only numbers
i know how show filed in newthread template and save data in database

PHP Code:

$this->validfields['user_contact'] = array(TYPE_STR, REQ_NO); 


but i want know how i make this filed (user_contact) Necessary and show erorr massage if user not entry anything Or user entry letters, not numbers ...
like Error message thread title

PHP Code:

you must enter a title / subject ! 


Thanks !