Configure Cisco ASA 5505 Firewall for DDoS Protection w/ASDM

My site has been getting a lot of DDoS attacks lately. I recently purchased a Cisco ASA 5505 Firewall for my Godaddy Server and while it's stopping most of the attacks, some are still getting through. I'd like for someone to help me configure the Firewall to stop all the attacks and I'd like for someone to also explain to me what some of the stuff means, basically we'll be working together on this so that I know how to make changes myself in the future. My Firewall has a Cisco ASDM 6.1 monitor which lets you work on stuff with a GUI instead of command line. If you could also help me find and setup a software firewall which can also help stop DDoS attacks, that'd be a plus. My server is a Windows 2008 64-bit with Plesk.