wp-email Will Not Activate

Hello:

I have a WordPress blog at culturespill.com using the “MY Guitar” theme by Dordor, and recently I have been trying to activate the wp-email plugin to allow my readers to email my posts to friends if they want to. When I attempt to activate this plugin, I get the following error message:

Plugin could not be activated because it triggered a fatal error.

Fatal error: Call to undefined function: add_shortcode() in /home/content/t/r/a/traklwright/html/wp-content/plugins/wp-email/wp-email.php on line 287

I am a novice at this and I have no idea what this error message means. If anyone can offer a plainspoken solution to this problem, I would greatly appreciate it! Keep in mind that I am a novice with no code knowledge, so give me the “dummy” version if you can. Thanks so much!