Assuming you want to provide a downloadable version, check the bottom of the maps forum

Quick search shows a tutorials (both six years old, but didn't see anything obviously wrong):
www.planetminecraft.com/blog/how-to-upload-your-map-to-pmc-tutorial-guide/
[​Note this covers only uploading as a zip, but that's probably a good place to start.]

Possibly someone who does maps regualrly can provide something better/more current.

For a small (under 15Mb) map, you can upload directly to the site, for anything larger you will need a hosting company. [MediaFire is one such, but do some checking to find one that suites you].