I'm not sure how to fit an external light, taking it from a one-way switch & converting it into a Two-way, my kitchen light switch's are at either end of the room. So I went & brought a Two-way switch to fit in next to the back door of my kitchen. How do I transfer power to the extra switch that I want to use? Do I use 'Pig-Tails'!

You need 2 three way switches and a 3 conductor with ground cable to connect things. Just how you connect things depends whether the feed runs to the light or one of the switches. I am not going to try to explain the different possibilities. Wish I would have saved the link to a good diagram tkrussel posted some time ago. Any basic electrical book will show it.

I'm not sure how to fit an external light, taking it from a one-way switch & converting it into a Two-way, my kitchen light switch's are at either end of the room. So i went & brought a Two-way switch to fit in next to the back door of my kitchen. How do I transfer power to the extra switch that I want to use? Do I use 'Pig-Tails'!
Most threeway scwitches have wiring instruction print (inside) on their box