There are various sites with which you can learn statistics. But probably these two side are more useful.
1. http://onlinestatbook.com/: This site gives you a simple start with statistics. If you have not learnt much statistics before, just start with this one. It can teach you linear regression.
2. http://www.statsoft.com/textbook/stathome.html: This site is much more comprehensive. Although it means for beginner as well, you should have already known a bit statistics to keep reading all the pages. More complicated tests, and multiple regression, are introduced in here. You may want to see this site as an upper level site, especially after you have studied the onlinestatbook.com
3. http://udel.edu/~mcdonald/statintro.html: People who are studying health sciences, public health, biology will see this site helpful. It is not any 'higher' than the statsoft.com, but it is more about biology and health studies. Plus, it has a very clear structure, which helps you differentiate between different types of test.
