I am moving my itunes library from an old computer onto a new one. What is the best way to do this.?

I have copied the itunes folder onto an external hard drive that I plan on leaving attached to the new system. How do I get the itunes library to read from the hard drive. Also I seem to have two folders with two different libraries, can I combine them without losing anything.I am moving my itunes library from an old computer onto a new one. What is the best way to do this.?
USB pen drive.I am moving my itunes library from an old computer onto a new one. What is the best way to do this.?
all you have to do is sync your ipod onto the new comp.