how can i update the registry key

i have to develop window registry for .exe where i have to first create registry key and then i have to read the registry key.after that i have to add the registry key but if the registry key is not same then update it and old version will be deleted.

 

means if it will ask for the update for the new version then it will update.

 

we have to published package into registry. 

 

please give the solution