Editing source code in Safari

I'm new to Mac and web design (currently doing a course and learning HTML code before going on to WYSIWYG). When editing HTML code in Windows XP, all I did was go to 'View' and 'Source' and I could edit from there. When in Safari, I can only view the source and not edit it. This may be a fairly basic question but I'm stuck. Appreciate any help on this matter (in simple terms please!)