Q: How do I use Bluetooth , when I turn it on it won't pick up other devices

You can only Airdrop through iOS devices, you cannot bluetooth transfer using iOS devices, what are you really trying to do.?

Using Airdrop is very simple for that you need your blueetooth on and you have to be connected to the same wifi as the other person whom you are trying to connect your device to.

Which other devices?

Please note that Bluetooth in the iPhone will connect to headsets, auto Bluetooth systems, speakers, keyboards.

iOS: Supported Bluetooth profiles