Hello Elle,
I suppose it is a little late now but the best thing to do is to get a cycling/sport mag or paper in which they give the teams taking part in the race and the name of the riders in each team. Don't buy it too much in advance though because changes can be made at last minute, just before they have to announce the team composition officially.
What you can do for now is google 'Tour de France'
and there you will see a link that gives videos, and teams compositions etc for this Tour. That might give you a better idea of what is going on at present.
I'll see if I can send you the link, but I don't guarantee anything !!!!!