How to access shared Macs on your network

Using the Mac's built-in file sharing capabilities, you can open and copy your files with other Macs and Windows PCs on your network. You can also specify individual users you'd like to share files with, and individual folders you'd like to share. You can even restrict those users' access, making it possible for them to only copy files, or providing them with the ability to write new files too. While AirDrop is convenient, file sharing is where the Mac's networking power really shines.

Open System Preferences.
Click on Sharing.

Check the box next to File Sharing.
Click on the + button under Shared Folders to share specific folders.
Click on the + button under Users to specify particular users to share files with. You can indicate whether you want them to have read and write access (so they can send files to you), read only (so they can copy files from you) or write-only access (so they can drop files to you in a specified folder, but can't see what's inside.

The Options button lets you share files using SMB, a common Windows file sharing protocol, and AFP, or Apple Filing Protocol, a legacy technology supported on some older Macs.