need help with upload

[eluser]Unknown[/eluser]
hi
im new in codeigniter
and i like it to much
im trying to do some website have users and news
but have some problem with uploading
like:

when user write news he can upload pic if he wants and i can do it perfect
but if he dosent want to upload pic it show message say "You did not select a file to upload."
ok i dont want show message i want to continue and insert news without pic

i'll give u example :

this's form and have :
title
news
pic --> this is uplad file


ok i need pic not required field
how to do that?


hope u understnad me, cuz im not very will in engish

thx alot