Question: how to untar gz on linux?
Answer: For tar. gz. To unpack a tar.gz file, you can use the tar command from the shell. Here's an example: tar -xzf rebol.tar.gz. ... 
For just . gz (. gzip) ... 
To run it: To run the executable file, CD to that directory, and type: ./rebol. (Or whatever the file name happens to be.)