How to activate unlocked iPhone 4s using Straight Talk?

I bought a used unlocked phone on ebay and have a 45 dollar Straight Talk service card and at&t sim card but I'm very confused on how to activate it? I don't have any kind of red activation card do I need it?

Can I use my Iphone at at&t, or sprint?

Cause I bought it at walmart from verizon. It is a Iphone 4S. I can't afford verizon anymore.

Added (1). I had verizon. But I want to get at&t or sprint and I already have the Iphone.

How to fix my old IPhone 3GS?

My old IPhone 3GS won't fully turn on! It has showed the apple sign for about three days now, we took it to gte fixed but it only made it worst! Does anyone have a way i could fix it?

Can I make a song with just 2 electric guitar?

Me and my friend are making a song for a project in biology (20% time project, we can do whatever we want).

We both know how to play guitar, but neither of us knows how to play drums and bass, so we cannot record them separately and put them all together.

If we make a song with just two electric guitars, will it sound good, or will it sound empty and unprofessional?

BTW, can I record with my iPhone 4 or my laptop, or do I need to buy good microphones to record the audio?