When you've converted all 18 frames to bitmap, open the Bitmap Gallery (located on the upper right side of the Property Bar). Select all the frames (you can use either Ctrl click to select one frame at a time, or select the first frame, scroll down to the last frame and Shift click on the last frame to select the lot.) Click Save. Name your animation and chose the Animated Gif option (the default). Click Save.

When the Gif Export Bitmap Options dialog opens, make the following selections: 8-Bit color depth, Browser Palette, and Dithering, none. Click Export.

Click on the New Animation icon in the upper left portion of the Property Bar (next to the new page icon) to enter the Animation portion of Xara 2.