as far as i know IF have real time weather/winds, i have read a topic about checking wind conditions and jet streams, among the recommends was Windy.com!
this site allows you to monitor wind conditions up to FL450 including the winds direction, so i wonder if i can use this site as a reference to make my flight plan?
You can definitely use it! The winds you see on windy.com should correlate to winds in IF. IF uses what’s known as winds aloft, which can be found at the following link.
Note: the above link doesn’t have worldwide coverage, while windy.com does.
Windy.com is good for getting a general idea as to what the winds are doing aloft. But please do check out #tutorials for other flight planning tips as DiamondGaming suggested. Thanks!