There are several videos on YouTube that explain how to analyze truss structures.
https://www.youtube.com/watch?v=1UugzngfMb0
https://www.youtube.com/watch?v=3WsFm8NnHNo
https://www.youtube.com/watch?v=FtSnue-TESg
https://www.youtube.com/watch?v=N4EMVI25LXI