First of all, to redirect a certain output of the command-line we have to use the symbol ">".
Even in this case, we will use a file named "Hello", in which we want to move a certain output, like "Sun".
$ echo Sun > Hello
So if we copy the the file on our command-line, the output will be the following:
$ cat Hello
Sun
If we want to move a certain output to an existing file, we just have to use twice the ">" symbol.
$ echo Bright >> Hello
$ cat Hello
Sun
Bright
To redirect an input from a file for a command, you have to use symbol "<".
In fact, it's not useful, as the result that obtain is just the content of the file.
Redirecting inputs becomes useful when it comes to chaining, so let's see it.