Here are some useful sites on the web to explore:
Sites offering a crash course in genetics are numerous and vary enormously in detail and complexity. If you want to begin with Mendel then there are a number of good sites including the Wikipedia entry about him: http://en.wikipedia.org/wiki/Gregor_Mendel.
If this appears rather demanding or assumes a lot of knowledge (although you can follow terms you don’t know by clicking on the hyperlinks) then go first to the Basic Principles of Genetics materials at: http://anthro.palomar.edu/mendel/Default.htm or at: http://www.athro.com/evo/gen/geframe.html.
For the history of genetics at a glance it might be a good idea to maintain a link to one of the many timelines that are available on the web such as this one on the BBC news site which was provided to coincide with news of the imminent publication of the human genome in 2000: http://news.bbc.co.uk/1/hi/in_depth/sci_tech/2000/human_genome/749026.stm
