/Library/LaunchAgents/boot-script.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Label</key>
<string>boot-script</string>

<key>ProgramArguments</key>
<array>
  <string>/usr/local/bin/boot.sh</string>
</array>

<key>RunAtLoad</key>
<true/>

</dict>
</plist>

/usr/local/bin/boot.sh

#!/bin/bash

function startup(){

    cd /Users/FooUser/Desktop
    touch FooFile
}

startup;