Try this:
make sure you are not in root.
What does it say?
Do you have the file in your home directory?
Who owns the file?
Make sure you are the owner.
If you are not then,
Code:
sudo chown <yourself> <filename.tar.gz>
Secondly, try downloading it again.
Maybe the file is corrupt.
Thirdly if you own the file, and have kde you can extract the file using Konqueror and probably ARK though I have not used it. Then open a terminal
Code:
cd <file location>
for example
cd /home/myself/file.1.0
Then read the README/INSTALL instructions.