Internet problem using samsung mobile

Hello Every one,
I have a bsnl connection in samsung mobile and gprs is activated .I can browse internet but the problem arise when i try to connect inter through mobile .PC suite is installed properly.when i try to connect internet from the PC Suite menu the details are coming up for network service provider but I couln't edit the APN and number and as result I cannot browse the internet .the values are highlight and I have the value of APN and number suplied by BSNL.how to do Please advice anyone??