String operation in the script

Hello,
Please help me, I have task in script to pick certain words (string)
Example :
:global spidey red,green,blue,black,white

how can I get string the blue one, from spidey variabel?
Thankyou

Apikson

Use the Force Apikson, use the Force … http://bfy.tw/ClfX

Thankyou for your respond