How can I define a feature within a DNA sequence?
Select the Sequence Region

Select the sequence region that will be labeled with a feature. In this example, a multiple cloning site (MCS) has been selected in Sequence view.
Add a Feature

To add a feature, click Features → Add Feature... .
Specify the Feature Name, Type, and Directionality

(1) Type the name of the new feature.
(2) Specify the feature type (according to GenBank conventions) and directionality (nondirectional, forward, reverse, or bidirectional).
Choose the Feature Color

Click the "Color" button. Choose a standard color, or click More Colors... . To display the feature as a thin black line, click No Color.
Enter a Description Qualifier

If desired, enter a description in the "/note" qualifier field. The buttons above this field allow the text to be formatted, and allow a symbol character or hyperlink to be inserted.
Once the feature has been created, mousing over the feature will display the contents of the "/note" qualifier field in a tooltip.
View the Feature

Click OK to see the new feature.