Click File > New > New Animation
Determine the size, background, etc. Click ok.
This would give you something similar to what I have in the previous interface screenie.
You should have the window showing frame one, and another window with "untitledX" (X being a number).
Use the button with the + sign under the frames to add a second frame (assuming you want 2 pictures/frames), if you want to add more, add more!
Open the other graphics you wish to use for frames, using "File > Open". They will open in other windows in the application.
Select the graphic for the first frame, click edit/copy.
Click back on the "untitledX" window to get back to the animation.
Select the first frame in the window showing frames, and then click the "untitledX" box again.
Click Edit > Paste > As new layer.
Select the graphic for the second frame, click edit/copy.
Click back on the "untitledX" window to get back to the animation.
Select the second frame in the window showing frames, and then click the "untitledX" box again (which now shows the first graphic).
Click Edit > Paste > As new layer.
The second graphic will now appear in the "untitledX" box, but if you look at the frames in the window below, the first frame should still be the first graphic.
You can adjust the time each is displayed by selecting the frame, and setting the "Frame Delay".
The instructions indicate you should click File, and then Export, and use the Export Optimizer to export a GIF file, but I couldnt do that in my version. It DID let me "Preview in browser" which then allowed me to right click the previewed file, and save to my system.
My review of this application would rank it pretty low in animation editing capability (the version I have anyway, which is a freebie and appears to be missing some features). I've seen much easier applications to combine multple images into an animated gif file. Most cost money though, as the "GIF" file itself is specially licensed usually requiring those that author applications that create the format to pay some royalties.