Here are the detailed instructions:
In the file lib/weblib.php search for the lines
if ($backmod) {
$backmod = "<form action=\"$CFG->wwwroot/mod/$backmod->mod/view.php\" target=\"$CFG->framename\">".
"<input type=\"hidden\" name=\"id\" value=\"$backmod->cm\" />".
"<input type=\"submit\" value=\"<\" /></form>";
}
if ($nextmod) {
$nextmod = "<form action=\"$CFG->wwwroot/mod/$nextmod->mod/view.php\" target=\"$CFG->framename\">".
"<input type=\"hidden\" name=\"id\" value=\"$nextmod->cm\" />".
"<input type=\"submit\" value=\">\" /></form>";
}
and replace them with
if ($backmod) {
$backmod = "<a href=\"$CFG->wwwroot/mod/$backmod->mod/view.php?id=$backmod->cm\" target=\"$CFG->framename\">".
"<img src=\"$CFG->pixpath/t/left.gif\" alt=\"<\" /></a>";
}
if ($nextmod) {
$nextmod = "<a href=\"$CFG->wwwroot/mod/$nextmod->mod/view.php?id=$nextmod->cm\" target=\"$CFG->framename\">".
"<img src=\"$CFG->pixpath/t/right.gif\" alt=\"<\" /></a>";
}
You will probably want to use other images than right.gif and left.gif. Those are the icons usually used only for moving things right or left.