The first thing you will need to do is visit one of the websites I listed below. Start entering names for your tree. Start with yourself, siblings, your parents and grand parents. Get the information entered into a secure website or a computer program. The easiest way to get information written down is either through a computer program or a website such as Ancestry.ca or My Heritage.com. Once you start your tree online you can get your family involved. Invite them to look at your tree online and they can help add to it for you. You can also start taking advantage of these websites to find your family. There are millions of family trees listed with these website that are searchable. It is very user friendly and I am sure you will enjoy the process. I have found many many websites that have helped me find not only people, but geographical information as well.
So first of all here is a list of places you can visit to get started.
http://www.myheritage.com/ Offers an excellent downloadable *free* program to get you started.
Once you get started you won`t want to stop. It is an ongoing process that you can keep coming back to and constantly find new information.