client.on('guildMemberAdd', guildMember =>{
  let welcomeRole = guildMember.guild.roles.cache.find(role => role.name === 'YOUR ROLE MEMBERS EXACT NAME');
  
  guildMember.roles.add(welcomeRole);
  guildMember.guild.channels.cache.get('WELCOME CHANNEL ID').send(`Welcome <@${guildMember.user.id}> to our server!`)

});