To add linetype, we need to first load a linetype in the drawing. The linetype menu is in the Properties panel, as shown in the following figure:
As you can see, by default, there are only three linetypes – ByLayer, ByBlock, and Continuous – and they all make a solid line. To load a linetype, click on the Other... option in the linetype menu and the Linetype Manager window will open up. Click on the Load... button of this Linetype Manager window and a new window with a list of all available linetypes in AutoCAD will open up: