% gunzip -c stk.tar.gz | tar xvf -
Then go into the stk directory.
To build and install stk under Unix, use the 'build' script. cd to the top
level directory of the stk distribution, and say ./brg/build DIRNAME
where DIRNAME is the directory you want to install stk in. You can
leave off the DIRNAME and STk will be installed under /brg/install which is
useful for testing purposes. However, you probably want to supply a directory
name, such as /usr/local.
The stk/brg/build script does all these things by calling other scripts in the stk/brg directory, so you can edit the stk/brg/build script to inhibit building of pieces which don't need to be rebuilt. For example, if you only want to build stk and don't want to install it, you can put an "exit 0" after the line which does "gmake $makearg" in stk/brg/build.
The stk/brg/build script doesn't support things like "make clean", or uninstalls, etc., because the underlying Makefiles are broken. If you want to start a new build, blow away the tree and start over.
Instructional building instructions.