Now that you have the basics, it's time to read the documentation :)

$ perldoc Tk::Button
BUTTON(1)             User Contributed Perl Documentation            B
+UTTON(1)

NAME
       Tk::Button - Create and manipulate Button widgets

SYNOPSIS
       $button = $parent->Button(?options?);

STANDARD OPTIONS
       -activebackground -activeforeground -anchor -background -bitmap
       -borderwidth -compound -cursor -disabledforeground -font -foreg
+round
       -highlightbackground -highlightcolor -highlightthickness -image
       -justify -padx -pady -relief -repeatdelay -repeatinterval -take
+focus
       -text -textvariable -underline -wraplength

       See Tk::options for details of the standard options.
[download]

borderwidth is described in Tk::options:

       Name:     activeBorderWidth
       Class:    BorderWidth
       Switch:   -activeborderwidth
           Specifies a non-negative value indicating the width of the 
+3-D
           border drawn around active elements.  See above for definit
+ion of
           active elements.  The value may have any of the forms accep
+table to
           Tk_GetPixels.  This option is typically only available in w
+idgets
           displaying more than one element at a time (e.g. menus but 
+not
           buttons).
[download]

Further digging is up to you.

As a side note: the book Mastering Perl/Tk is a very good reference. Learning Perl/Tk is not.