Please use code tags .
In C#, you need a semicolon at the end of every executable code statement; for instance, after “Print(Hello_World)” inside of your Start() method.
That is probably not the only error in your script. Instead of “Print”, I think you meant to use either “print” (lowercase) or “Debug.Log”. Also you probably meant to print a string rather than a typename, which means you need to put quotation marks around the text you want to print.
In computer programming, you generally need to write things exactly perfect or they just won’t work at all. If you’re new to programming, I suggest you find and follow a tutorial with explicit examples.