Hiya, I am a phone/computer noob - please be kind

I am able to connect my blackberry to my apple computer. It asked for a username/password and APN number.

I don't have these on my phone so I pressed continue and I'm connected. All is good. HOWEVER.....

My husband says, "Oh, does that mean anyone can hack into your phone?"

I have a password you have to type from the keypad to open the phone but
this APN number, username and password are not set.
For security - do I NEED a username/password and APN number? Should I set one?

THanks for your help.