You will need to get and install a program called TeX, or a work-alike, like LaTeX or emTeX. They are not part of djgpp! Then run your TeX work-alike on the docs' source files (called *.txi or *.tex) which you get with every *dc.zip file you download. Alternatively, you can get two programs: texi2dvi and dvi2ps, then run them in sequence on the same *.txi files to produce a PostScript file which then can be printed on a PostScript printer.

Note that some docs files (notably, those for gcc) will produce voluminous print-outs. You have been warned!