Now that you can compile&run helloworld you may wish to know where to find additional help files (for example, the files on which this Guide is based). I will list here other utilities that may help your programming.
xMate, downloadable from http://www.andywos.ih.co.za/xmate/, is an IDE, i.e. it offers a project manager, an editor and will help you to manage your sources. It is a Windows program developed with Harbour but uses a non-open source GUI library. See here for help in getting, configuring and using it.
At http://sourceforge.net/projects/xbasemode you may download an xBase mode for GNU Emacs.
MiniGUI (http://www.geocities.com/harbour_minigui/) offers a quasi-RAD development system for xHarbour, the compiler, an Open Source GUI library and a friendly setup program and so is perhaps the favourite choice if you are a true beginner that wants to start quickly. It is a Windows program and supports only the Borland C++ Compiler.
A set of Norton Guides, including documentation for Clipper from Summer 87 to Clipper 5.3, and also for Clip-4-Win version 3.0, Blinker 5.1, Harbour 0.37, and other tools is located in this good website worth a visit: http://www.clipx.net/norton.php.
I thought this link would last more. Have a look at http://www.itlnet.net/Programming/Program/Reference/cs87/menu.html and http://www.itlnet.net/Programming/Program/Reference/c53g01c/menu.html.
The reference link is http://www.itlnet.net/Programming/Program/.
I recently discovered a pair of basic tutorials - yet complete - in Spanish. One is contained in this page: http://www.elguille.info/Clipper/manual.htm (if you know Spanish and want to print it, it's about 50 pages long). The second tutorial is compressed in a zip you can download from http://mx.geocities.com/maghtin/manuals.htm (the file is named clipper5.zip and it contains a 33-page pdf file).
I see at http://freshmeat.net/browse/67 that FreshMeat holds tutorials has well - if people want to, I can put this guide there. E-mail me please.
I will surf to know what's in The Oasis (http://www.the-oasis.net/). They included a link to this Guide and seem to have a large archive of Clipper material.
Another interesting source is http://www.lnf.infn.it/Calcolo/doc/AppuntiLinux/a2471.html.