Upload the entire nikeipod-stats folder to your Wordpress plugins folder (/wp-content/plugins/)
Activate the plugin through the 'Plugins' menu in WordPress
Go to the Design–>Widgets page and drag the NikePlus Stats widget to your sidebar
Choose the option to Edit the widget and provide your Nike+ user id, which is NOT the user name that you use to log in to the nikeplus website.
Your Nike+ user id is a 10 digits number (or maybe longer) that you can get as follows:
1) Login into nikeplus website.
2) Display your runs.
3) From the menu "share", choose the "grab the link" option. You have now copied the link to your runs.
4) Go to Notepad or any other text editor and paste the link.
5) Get your user id at the end of the link you just pasted.