Combining
Now there are two ways to proceed. In the first way, pick the gradient
tool from the Synfig Toolbox, and click into the canvas once. You should note
that another layer was added in the Layers Dialog called 'Gradient'. This is
nothing special. If you see no gradient but just a plain color, pick the normal
tool, click into the canvas to acivate the gradient's ducks. You need to grab
the one you see and move it a bit until a gradient appears.
You now have a gradient but it is not what you wanted: It spreads the
whole canvas and the goal was to have a gradient on the rectangle. Let's fix
this now.
Select the gradient and the rectangle layer in the Layers Dialog. They
should appear with a blue background now. Then, context-click (ie. right-click
on Windows and Linux) and select 'Encapsulate' from the menu. The view of your
layer tab should change now, showing a small box called 'Inline Canvas' with an
arrow in front. If you click the arrow, it will unfold and show your previous
two layers; the gradient and the rectangle.
You can treat this layer like any other layer -- move it around,
duplicate it, copy and paste it. You'll notice an arrow next to the icon of the
box. By clicking on this arrow, you can expand the inline canvas to see its
contents.
If you want to change the name of it to something more descriptive, just
select the layer in the layer tab and click on its label. Then you just edit it
in place. You can do this for ANY layer, and are strongly encouraged to do so.