Make sure you backup or save your existing customizations like links and sidebar addons, hit counters, etc. before deleting because they will be replaced by the new code. After installation just copy and paste your customizations back in.
Your blogs title will automatically replace the title you see in the header. The "description" will display at the top below the title, edit it in your blogs "Settings" area
If you have any questions or problems please ask in the comments, don't email me directly! I will offer tech support through the comments only!