Wouldn't it be unfair to conceal our small masterpiece from the rest of mankind? Let's save it for the Web too!

1. Pull down menu File > Save for Web... A huge dialog window appears. This dialog lets us optimize image quality / file size ratio visually.  It is important to save images at the smallest file size we can, without sacrificing too much of the image quality, to minimize the download times of the web page they appear on. This is known as image optimizing.

2. The image is positively too large for web publication. Reduce target image size as it is shown on animation.

3. Now we must select a format. There are 4 options there; most popular of them are JPEG and GIF formats. JPEG images (with a .jpg file extension) are the best suited to photo quality images, while GIF format is better for graphics such as text, logos and cartoon type images  
So, let it be JPEG at this time.

4. Now look at the target file size (under the preview area). We can reduce it by using the Quality slider (movie).

5. Click OK, choose a target folder and file name and save the image.

Note that command Save for Web creates a Web optimized copy, not affecting the original image file.