BillyJones;
Hello and welcome to the forums.
In addition to defining share permissions, you also need to define NTFS permissions using the security tab in the properties of the shared folder or file. Additionally you may find it useful to make sure that an identical username and password (with the appropriate permissions) is common (present) on both peers not mandatory as you should still receive a prompt to submit a username and password when accessing a share on one machine from another, it just makes things simpler and may help alleviate some confusion. Without these in common, when prompted for credentials, use the following format
MachineNameHostingShare\UserNameOnThatMachine
PasswordForThatUserOnThatMachine
Keep us posted.
Randy