how to add new word into dictionary when sms

[pclum]

I am using the LG Optimus 2x, when I sms and encounter some word that there is not exist in the dictionary, how to add to the dictionary ? anyone can enlighten me ? I remember when I use samsung omnia II last time ( it is a window phone ), it remember new word and add into the dictionary but this LG 2x don't do that.

Thks in advance