This allow to put some html code in header (or example metatags) and footer (for example counter code)
There is no admin part for two reasons :
1) I’m learnig how it works
2) I’m not sure it would be a great idea to have a DB request for a code that never change
So for instance you’ll have to edit manually the plugin file
Why use a plug in instead of a direct ad in the template ? because for alpha release the default template (my own is based on kakumei) sometimes change, so keeping the personal code updated each time can be tedious.