From Xojo Documentation

Property (As Boolean )

aWebCheckBox.Value = newBooleanValue
BooleanValue = aWebCheckBox.Value

New in 2010r5

Supported for all project types and targets.

Gets or sets the state of the WebCheckBox: checked if True, unchecked if False.

Sample Code

Test to see if the user has checked the CheckBox:

If CheckBox1.Value Then
End If

You can also check the CheckBox in your code:

CheckBox1.Value = True