Blackberry curve wifi ?

[la77amx1]

i have a blackberry curve which never connects to a wifi network. it does connect but doesnt use the wifi to browse the internet. i have to have a data plan in order to use the wifi. when i disable the data service i cant browse using the wifi. i dont want to use the data service because its too expensive where i live. so how can i browse the internet on my BB with wifi and not use the edge or 3g ? thanks