Simply asking to provide an example without showing what you’ve done yourself can quickly end in a “What have you tried?” and/or “What research have you done?” reaction. Therefore, I can not really advise to simply ask for an example.
But if you provide your own example, explaining what you have tried, and what exactly you are having a problem with… then you’ll have a pretty good chance that Crypto.SE members will help you understand what you might be missing. In the end, the general consensus tends to be that it is important for you to understand things and therefore people like to see that you invested some time and effort trying to research, learn and solve things yourself.
Simpler said: if you present your own example showing what you have done, and explain where you’ve hit a problem in your example, you’ll have good chances to recieve all the help you need.
Can I ask in crypto.stackexchange.com to do an example for me …
You can try, but I would not advise it (for the reasons explained above).
review my example where it went wrong or to improve my example to work correctly?
Yes, that should work… just don’t forget to explain what you tried and where you’ve hit a problem. The more information you provide in your question, the better people can help you understand things.