I am trying to see where is my c1 but i keep getting Expected identifier, got '['
print (game.Workspace.R15.["RightLowerArm"].Weld.C1)
You have a period before the '['. Simply remove the period.
Change
print (game.Workspace.R15.["RightLowerArm"].Weld.C1)
to
print (game.Workspace.R15["RightLowerArm"].Weld.C1)