New XP User needing help with printer sharing

I followed all of the steps to network my two machines (both with XP
Professional), including sharing the printer and giving it a name. My main
machine can see and access the files on my second machine with no problem.
But my second machine, while seeing my main computer on the network, does not
let me access any of the files (I get a message that says: "You do not have
access to the folder "Main Computer.") And when I try to add the printer
connected to my main machine to my second machine (by browsing), again, I see
my main computer listed under the network, but when I double-click on it,
nothing happens. Shouldn't it show me the printer that I've designated for
sharing? Is it the same reason why I can't access the files on my main
computer from my second machine (even though I can see the main computer on
my second machine)?

Please help. Thank you!!