The web is always a helpful place to look for resources. There are numerous websites out there with geometry help. I have even found geometry video lessons on YouTube. If you are having a hard time with a concept then just google that concept and thousands of entries should be found. A concept may make more sense to you after you have heard about it in class and then looked it up online. Here are a couple sites that I have used and found helpful.
http://www.math.com/homeworkhelp/Geometry.html
http://www.mathleague.com/help/geometry/geometry.htm
http://library.thinkquest.org/20991/geo/index.html
http://mathforum.org/dr.math/faq/faq.formulas.html
http://www.doe.virginia.gov/VDOE/Assessment/Manipulatives/GEOMETRY_BP2003.pdf