What do I need to turn my speedlite Di466 flash in to a slave flash for my Nikon D3100?

Hi, I'm looking to get a bit more creative with my pictures. Looking at some on line tutorials and I'm needing a slave flash.

How do I trigger my speedlite flash gun when using my Nikon D3100?

Quite new to this so feel free to give me the big writing and picture version.

Here is the instruction manual: http://www.nissindigital.com/files/en_di466_users_nmanual.pdf

Here are your options:

1) Built in optical slave called the "Wireless Remote Flash System" this allows it to slave off your pop up flash with the flashgun running in manual mode. It's crude but effective and can deal with flash systems which preflash, but can fail when in brighter conditions.

2) iTTL compatible cable. This is the cheap way of getting TTL flash metering off-camera.http://www.amazon.co.uk/i-TTL-Camera-Flash-Extension-Cable/dp/B0074JGIYM/ Problem is you are limited by cable's length.

3) Cheap TTL trigger. Gives you good range and reliability in all conditions, may not give you every bell and whistle.http://www.amazon.co.uk/...005VM1DW6/

4) Pocketwizard TT1/TT5 http://www.amazon.co.uk/Yongnuo-2-4GHz-Wireless-Remote-Control/dp/B005VM1DW6/ Yes it's expensive, but the Gold standard.