This should get you started.
Dim objRS, Layer, Bookmark, X, Y, MaxDistance
Set Layer = Map.Layers("LayerName to search for")
MaxDistance = "1000" ' Distance is in map units
' Select the nearest point
X = GPS.X
Y = GPS.Y
Set objRS = Layer.Records
Bookmark = objRS.FindNearestXY(X, Y, MaxDistance)
Call Map.Select(Layer, Bookmark)
' Show the attributes of the selected point
If Bookmark <> 0 Then
If Layer.CanEdit Then
Layer.Editable = True
Call Application.ExecuteCommand("featureproperties")
End If
Else
Call MsgBox("Nothing Found")
End If