Check out this tutorial firstly so you understand how these work.
Once you have a complete understanding, simply load into your flight, and plug in the waypoints on the chart. Follow those waypoints along with the required speed and altitude restrictions and you’re all set!
At the moment, there are no integrated STAR and SID charts available in IF. You’ll need to use third party resources to obtain these charts, and insert them manually. If you’d like to see these charts as a part of IF, vote here!