There are several different software application that can do this for you, such as Paint.Net. Although, if you want to learn how an easy way to shrink the image, follow the instructions below:
- Open the folder that contains the picture(s) you want to email to someone
- Right-click it and select 'Send To > Mail Recipient'
- In the Attach Files dialog, select the size (1024x768, 800x600, 640x480, etc.) of the picture that you want to send.
- Then press the Attach button.