I can recommend that you buy Web Developer and Web Design magazine from WH Smith or the like as these will give you some good free software. I you don't wish to purchase them then the software you will require is at best, Dreamweaver, Photoshop and some resources in learning HTML, XHTML, CSS and maybe XML also.
Check out sites such as:
http://www.w3schools.com
http://www.tutorialized.com
http://www.good-tutorials.com/
http://www.adobe.com
http://www.computerarts.co.uk
http://www.photoshopcafe.com
http://www.sitepoint.com
I would recommend that you learn to hand code HTML, XHTML and CSS though as Dreamweaver might be able to make a site for you but there will always be a time where you will have to edit something yourself and DW won't know how to do it effectively. If you are keen on getting into this then check out sitepoint.com and register for the forums. So much good info and advice and the people are really helpful also.
Good luck with the site !