How to Create an ICO File From a JPEG in Paint
Icons are special types of image files your computer uses to represent programs and file types. For example, when you look on your desktop, notice that the name of each program has a small picture above it -- usually, the program's official logo. These images are icons. Technically speaking, icons differ from ordinary image files in that they are always perfect squares and use the file extension ".ico" rather than ".gif," ".jpg" or ".png." Use Microsoft Paint to create your own ".ico" icon files.
Launch Paint and open an existing JPEG image file.
Resize your image so that it's a perfect square. Click the "Resize" button, which is located in the "Image" pane of the "Home" tab, and enter identical "Horizontal" and "Vertical" dimensions. Click "OK" to make your image a perfect square.
Press "F12" to open a "Save As" dialog box, Enter a name for your file, and select ".bmp" from the list of available formats. Close Microsoft Paint.
Locate the new BMP file using Windows Explorer. Click once on the file to select it, then press the "F2" key to rename it. Instead of changing the filename, change the extension from .bmp to .ico. If Windows pops up a warning, confirm your choice.