Don't use all-caps in titles again, otherwise I'll next time just remove the topic.
Just because you're a beginner doesn't entitle you to have others write all the code for you.
Start off by properly describing what you want. What is a rounded rectangle in your opinion? Does it need to be filled? Just have a border outline? Does it need to dynamically change size?
Then tell us what you have tried already. Did you look at the documentation to see what SFML provides? Did you think about, how a rounded rectangle can be achieved?
Programming is not about going to a forum and demanding to receive code that one can copy-paste, coding is about solving problems.