How does the right hand rule apply to the current in a long straight wire?
The right hand rule helps you to find the direction of the magnetic field caused by the current carrying wire.
Imagine grabbing the wire with your right hand with your thumb pointing in the direction of current flow. The way the fingers of your hand curl will give you the direction of the magnetic field caused by this current.
Just use your imagination when it comes to grabbing the wire - really touching a live wire is a big no-no!