Accessing files in ubuntu from windows 7

You just need to mount your windows partition. Ubuntu and its file manager, nautilus, make this easy by automagically doing all the work for you.

Open the file manager and you should see your windows drive listed in the side.

If it does not show up, or you are interested in how to mount partitions manually (its really just one command) then read the wiki guide:
https://help.ubuntu.com/community/Mount
https://help.ubuntu.com/community/MountingWindowsPartitions