Bought an iphone and can't put music on?

So i bought this iphone not new, it is used but i can't delete his music off it and put mine on.
when i connect it to my comupter it doesn't show up in my itunes as a device but on my computer desktop it shows it is plugged in.

IPhone vibrating this is broke and need jus vibration for text?

Ok so the last person didn't answer what I was asking so. The switch on the side of my iPhone is broken):I'm wanting my TEXT and calls on just vibrate!(:is there anyway I can turn them on just vibrate? My switch won't turn anything on vibrate?!):for school anyway
Btw it's a iPhone 3G?! If that helps
*please no, you shouldn't have phone on in school anyway!**^or anything like this please

Why doesn't my iphone sync new songs?

I have songs in the library waiting to be synced, but whenever i click file on top of itunes, the sync option is gray? Why can't i sync new songs even if they are in my library?

Why do the songs on my iPhone get erased every time I try to sync it?

Every time I want to add a new ringtone, episode of a show, or movie, I get warned that all of my existing songs on my iPhone will be deleted. I get tired of having to refill all my songs everytime I want to add something new from my iTunes. Why does it do that and is there a way I can disable it or something?

If i buy an unlocked iphone on Ebay, can i use it on a virgin mobile plan?

I saw the iphone on virgin moble and it is a little more than i would like to pay for. I checked ebay and i was going to bid on an iphone in hopes to get it for a cheaper price. So i was wondering if i buy a "factory unlocked" iphone on ebay, would i just be able to go to virgin mobile's website and activate it?

Is there a real legit way to download free music into your iphone?

I did limewire but alas! Forstwire doesn't work on my computer, i don't know.one of my brother's friends has about 900 songs in their itunes icon on their phone and they did it for free.how? Please share?

Where can I watch angus thongs and perfect snogging?

I wanna watch it for free. Any sites or something - I'm reading the book and wanna see If it's as good as the movie - also can you watch it on my iPhone for free?

How to ship an iphone and how much would it cost?

How should I ship my iphone 4? Can I put it in its original box or will they provide one? I'm shipping it from Toronto to Vancouver, how much do you think it would cost for a regular parcel?

Added (1). I'm sending it to a family member.

Where can I find my contacts that I synced onto my Mac?

I just synced my iPhone to my Mac laptop and I'm wondering where I can find them. And also, if you know, can I import them to a flash drive?

Is Bill Nye the Science Guy dead?

I was just on Facebook on my iPhone, and saw that one of my friends liked RIP Bill Nye the Science Guy and read that he died today on that page. I'm just wondering if this is true?