How do i get mobile internet on my samsung galaxy y

is the phone in airplane mode or is data turned off?
is 1g/2g/3g/4g disabled?
do you have signal?
do you have a data plan with the carrier (i would THINK so)?
is the phone set to data over wifi only?

have you tried asking your son how to use the phone?

android phones should default to the correct settings to access the web. just open the browser up and you have web.... unless someone changed a bunch of settings or options.... or if you have no signal....