Combining Objects into Blocks - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 354

Now let's see how this process works when you want to get a block from
another drawing:
1. On the left side of the DesignCenter, click Blocks in the list under the
07A-FPLAY4.dwg drawing.
On the right side, the list of blocks in that drawing appears (see the
top of Figure 7.55).
2. Click A-DOOR-36IN in the right panel, and then, if necessary, click
the Preview button at the top of the DesignCenter.
A picture of the block appears in the lower-right corner of the
DesignCenter (see the bottom of Figure 7.55). You can resize the pre-
view pane vertically.
3. Open the Layer list, and make A-DOOR the current layer.
FiGuRE 7.55 The DesignCenter with Blocks selected (top) and with the
A-DOOR-036IN block selected and Preview turned on (bottom)