The StackPanel is a layout control that allows you to organize controls one beside the other or one below the other. You can select the orientation by using the Orientation attribute on the element. Many other controls use the StackPanel internally to layout controls like the Menu, ComboBox or ListBox.
Below you can check a simple example:
If you want to stack the items inside the panel horizontally, you just have to set the Orientation attribute in the element to Horizontal like in the sample below:
Add padding to the StackPanel
If you want to add some padding to StackPanel, you can combine it with the Border control and then add the padding to the Border element as shown in the XAML markup below: