(I used xchm, HL)
You can use either kchmviewer or gnochm or xchm.
kchmviewer from KDE
kchmviewer is a CHM (Winhelp) files viewer written in Qt/ KDE. It can be build as a stand-alone Qt-based application or a KDE application. The main point is compatibility with non-English CHM files, including most international character sets. It has the features set of standard viewer: search (including non-English CHMs), bookmarking, font size changing, index/content browsing, codepage support, and more.
Install kchmviewer Using the following command
sudo aptitude install kchmviewer
gnochm from Gnome
GnoCHM is a CHM file viewer for GNOME. It is implemented in Python, using the PyCHM bindings for chmlib.
Install gnochm Using the following command
sudo aptitude install gnochm
xchm
xCHM is a cross-platform GUI front-end to chmlib, with borrowed bits from Pabs' chmdeco project.
Originally written for UNIX systems (Linux, *BSD, Solaris), xCHM has been since ported to Mac OS X and Windows.
xCHM can show the content tree if one is available, print pages, change font face and size, remember bookmarks, display a searchable index, and search for words in the current page and the whole book.
Install xchm Using the following command
sudo aptitude install xchm