Simply wrap scrolling content in a scrolling control like ScrollViewer
:
<!--ContentPanel - place additional content here-->
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"/>
<ScrollViewer>
<toolkit:HubTile x:Name="GuidanceButton" HorizontalAlignment="Left"
VerticalAlignment="Top" Grid.Column="0" Grid.Row="1" Background="#FF12AFC7" GroupTag="StaticHubTile" Tap="Button_gridbut_Click" Margin="30,10,0,0" Size="Medium" Source="/Images/sharemedium.png" />
<toolkit:HubTile x:Name="JourneyButton" HorizontalAlignment="Left" VerticalAlignment="Top" Grid.Column="0" Grid.Row="1" Grid.RowSpan="2" Background="#FF12AFC7" GroupTag="StaticHubTile" Height="169" Width="169" Margin="72,230,-1,0" Grid.ColumnSpan="2" Tap="Button_gridbut_Click" Source="/Images/facebook.png"/>
<toolkit:HubTile HorizontalAlignment="Right" VerticalAlignment="Top" Grid.Column="0" Grid.Row="2" Background="#FF298391" GroupTag="StaticHubTile" Size="Small" Margin="0,99,-1,0" Height="82" Width="82"/>
<toolkit:HubTile HorizontalAlignment="Right" VerticalAlignment="Top" Grid.Column="1" Grid.Row="1" Background="#FF298391" GroupTag="StaticHubTile" Size="Small" Margin="0,45,148,0" Height="82" Width="82"/>
<toolkit:HubTile x:Name="searchButton" HorizontalAlignment="Right" VerticalAlignment="Top" Grid.Column="1" Grid.Row="1" Background="#FF12AFC7" GroupTag="StaticHubTile" Size="Default" Margin="0,137,61,0" Grid.RowSpan="2" Height="169" Width="169" Tap="Button_gridbut_Click" Source="/Images/camera.png" />
<toolkit:HubTile HorizontalAlignment="Right" VerticalAlignment="Top" Grid.Column="1" Grid.Row="2" Background="#FF298391" GroupTag="StaticHubTile" Size="Small" Margin="0,7,148,0" Height="82" Width="82"/>
<toolkit:HubTile x:Name="routeButton1" HorizontalAlignment="Right" VerticalAlignment="Top" Grid.Column="1" Grid.Row="2" Background="#FF12AFC7" GroupTag="StaticHubTile" Size="Default" Margin="0,99,61,0" Grid.RowSpan="2" Height="169" Width="169" Tap="Button_gridbut_Click" Source="/Images/status.png" />
</ScrollViewer>
</Grid>
Also, remove the last RowDefinition
since you are not using it and it will break your view in half.