rocker panels cab corners

[no-tilt]

I am totally new to this site, that is because I never owned a c-10 before
Just ended up with my wifes grandfathers 71 c10 , it has been a farmtruck all it's life .
All bodyparts need replaced , allready found all used parts . engine/drivetrain is good,stripped truck down to just the cab and frame
Cab needs rockers inner and outer +cabcorners and cabsupports .Just picked up these parts , I have a mig welder, But I do not have a lot of experience welding sheetmetal
Could use some advice/pics on how to cut out the old rockers /corners/cabsupports and weld in the new ones

Thanks Elbert Koster Canada