How to use jenkins pipeline with nvm wrapper plugin?

I'm using pipeline (Jenkinsfile) and I need to change node version. i added the Nvm Wrapper Plugin but i don't know how to use it properly from Jenkinsfile

should i add the nvm('...') {} inside steps? or should it be somewhere top level in the node step? currently i don't even have the node step - everything is done using sh

what worked for me:

pipeline {
  agent any

  stages {
    stage("Build") {
      steps {
         nvm(nvmInstallURL: 'https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh', 
             nvmIoJsOrgMirror: 'https://iojs.org/dist',
             nvmNodeJsOrgMirror: 'https://nodejs.org/dist', 
             version: '8.1.2') {
                    sh "npm install"
                    echo "Build main site distribution"
                    sh "npm run build:dist"
              }
           }
        }
    ...