Switch to "Variable View" as shown in Figure 1.

Type the label of your variable into the "Label" column as shown in Figure 2.

Click on the "Value" column shown in Figure 2.

The following steps are shown in Figure 3.

Insert the numerical value you would like to use in the "Value" spot.

Enter the name that the number represents in the "Label" spot.

Click "Add."

When complete, click "OK."