No worries, glad to help!
You said you can see the computers on the network... does it show anything when you click on a particular computer? Such as a printer folder?
You can tell if a file is shared by looking at the drive icon (that little folder to the left of the drive name). If it has a cupped hand underneath it, it's shared. I think maybe yours are not, you have to manually share them, it's not an automagic thing.
To share: Right click on the drive you wish to share, select New Share from the drop down menu.
In the dialogue box, towards the bottom click on the button that says New Share. In the next dialogue box, it will ask for a new share name. You can just put whatever drive letter (such as C for the C drive) or give it a name such as "desktop's hurking hard drive". Ok all the way out and you should be able to see the drive now from another computer.
Hope this helps!