There are 2 ways to scaling a drawing in Autocad, Scaling by Factor and Scaling by Reference.
This tutorial will show you how to scale using Factor, you can read how to scale using Reference.
1 Open an AutoCAD file with lines/objects/groups/blocks/images that you can scale. If it’s a new file, just draw a line or insert an image.
2 Select what you want to scale.
3 Find the scale option. You can type “sc” or “scale” and press the spacebar/enter button, or in the ribbon, in the modify tab, find the Scale button (It’s a blue square with a smaller grey square in the bottom left corner. If it’s not in your modify tab, click the drop down arrow for more modify options.)
4 Specify your base point when asked. Your base point can be on the object itself or it can be anywhere in the workspace. You can even click a point on another object to use as a base point. You can for example select the edge of something, or the midpoint. Select your base point by clicking on it.
5 Specify your scale factor. Using method 1 (scaling by a factor), you can now type a number (a scale factor) and press spacebar/enter. Your object will change size according to that number. If you use decimals, the thing you want to scale will become smaller. Voila! You’re done!
Alternatively, you can scale by moving your cursor around. When you find a size that you want, just left click on the mouse to enter. This step makes it very difficult to scale down though.