Question: how to add ctb file in autocad 2018?
Answer: Click Application menu Print Manage Plot Styles. Find.
Double-click the STB file you want to edit.
In the Plot Style Table Editor, Form View tab, right-click the plot style that you want to copy. ... 
Right-click a plot style. ... 
In the Add Plot Style dialog box, enter the name of the plot style.
Click Save & Close.