There are many tools which will enable you to create clear, effective websites. 
However, if you are new at the game, it is helpful to

• gain an understanding of effective websites
• fit your concept into a process of design
• have fun creating your website!

Summary of design:

• identify your audience
  • motivate your audience:  treat them with respect and provide proactive feedback opportunities
  • establish clear, measurable web site objectives or design purposes
  • acknowledge reactions, effort & success, and built in help for failure to meet expectations
    
• Content
  • focus and define your website content
  • language should be simple, understandable for a global audience
  • promote scanning content for important concepts
  • build in white space
  • prioritize your information, as with an outline or concept map

• Navigation:
  • simple
  • clear
  • layered (site maps)
  • organized (think "outline")

• Incorporating graphics
  Developing websites begins with its text and structure.  After the basic structure is developed, the content should be analyzed as to what would benefit from illustration whether line or photographic graphics

  Principles:

  • choose a background and text colors with high contrast
  • use a browser safe palette
    to be consistent across platform and browser
  • format text consistently
    • avoid color changes
    • avoid italics (hard to read), color changes, and underlining (mistaken for links)
    • avoid overly-large text
  • avoid textured backgrounds
    that make it difficult to read
  • illustrate content with simple, symbiotic, scaled (small), stagnant (non-moving) graphics
  • avoid "dancing dogs": 
    graphics that show off but do nothing for content
  • file formats:  compressed (.jpg) photographs, and drawings in (.gif)