Summarize:

Before you can share files from your Windows 8.1 computer with the rest of your local network, you'll need to make the computer "discoverable." The PC Settings screen will appear. A list of networks will appear in the right panel. If you see more than one network listed, use the one that says "connected" beneath its name. Once you do this, the computer will be discoverable on the network, which means that other users on the network will be able to find the folder(s) you share. Now you'll get ready to share your first folder. This will launch the Windows File Explorer. Use the sidebar on the left to navigate your folder structure until you find the folder you want to share with other users on the network. Don't double-clickjust click once. Some sharing options will appear at the top of this tab. The "File Sharing" dialog will appear. " This allows everyone on the network access to this folder. You'll be able to define which type of access they have in just a moment. The folder is now shared with members of the network. To see your files, they can open the File Explorer and click the "Network" icon. " Now you'll decide the type of access that "Everyone" has. The Folder Properties screen will appear. This dialog shows all the security settings for the folder. This will open the "Permissions for [folder]" screen. If you don't see "Everyone" listed: Click "Add." Type "Everyone" into the blank. Click "Add." Under "Permissions for (Everyone)", decide what sort of access you'd like to provide: Full Control: Allows everyone to read, delete, and edit files in this folder. This also grants this user the ability to change permissions on the folder. Change: Allows everyone to read, delete, and edit files in the folder but not change permissions. Read and execute: Allows everyone to view files in the folder and run programs. Users cannot modify files in the folder if this is the only option selected. List folder contents: Allows users to see a list of files in the folder. The files are now accessible by users connected to your network.
Press Win+S to launch Windows Search. Type "PC Settings" and press Enter. Click the "Network" link. Click the name of the network you're connected to. Flip the "Find Devices and Content" switch to On. Press Win+S to launch Windows Search. Type "Explorer" and press Enter. Navigate to a folder you want to share. Click to highlight the folder you want to share. Click to the "Share" tab at the top of the Explorer. Click "Specific People" in the "Share With" area. Type "Everyone" into the box and click "Add. Click "Share" to share the folder. Right-click on the shared folder and select "Properties. Click to the "Security" tab. Click the "Edit" button. Select "Everyone" from the "Group or user names" list. Set the permissions for the user(s) you selected. Click "OK" to save your permissions.