For an English language video tutorial check here - thanks to Koz4Christ

There are a few things to verify before installing Multiverse-Portals.

• When running other Multiverse modules (such as Portals, ensure it's the same version as Multiverse-Core. For example, if Multiverse-Portals is 4.0.0, Multiverse-Core should be 4.0.0.
• You must have Multiverse-Core before having Multiverse-Portals.

Grab the jar. Download the Multiverse-Portals JAR from the release site or grab a dev build from the Multiverse 2 Jenkins

There is NO Zip package available. Multiverse-Core (and MV Plugins) will create default configs for you on the first run.

*Optional: Install the Multiverse-NetherPortals plugin!

Place it in your plugins folder like so:

Start your server and make some portals!