How Do I Activate My New Lg Phone After Initially Selecting The Incorrect Phone?

I purchased a LG800G phone tonight at Wal Mart and when I was filling out the activation forms I began by selecting the wrong phone.  All I saw were pictures and though the one that looked like mine was it; I failed to realize there was a LG icon provided.  The phone did not come on when I completed the forms.  So, I guess the reason is because I put in the wrong phone model.  Also, I entered the unlimited airline pin I purchased.  So, how do I fix this?  I need this phone ASAP.