Your Mac has various ways to share files with others, including AirDrop, but for a quick, cross-platform way of doing so via a web browser, open a Terminal window (it’s in the Utilities folder of Applications) and type the following:
twistd -n web --path .
Note that’s a period/full stop at the end of the command, and it must be typed. This will share your home directory’s contents.
Then tell others on your network to visit your IP address in their browser, adding :8080 to the end of the address. For example, if your Mac is using address 192.168.1.5 then they would type the following into the address bar of their browser:
When you’ve finished with your server, tap Ctrl+C to quit it.
If you find the above twistd command doesn’t work, try the following instead:
python -m SimpleHTTPServer 8080