Scripts to synchronize Todoist and habitRPG

todo.rb

# Simple script to synchronize Todoist and habitRPG
# only marks complete items in Todoist as complete in habitRPG,
# doesn't synchronize non-complete to do items
#
# Note: this script uses a temporary file to store the most recent sequence number from
# Todoist. Therefore, it must be stored in a spot where it has write access to a new file,
# and if you move it you'll either need to comment out the body of the loop below or else
# move the file.
#
# If this is the first time you're running the script, you might want to comment out the
# body of the loop below so that it doesn't synchronize everything in your history.
#
# (Commenting out the loop body and running the script will just update the sequence number
# and not actually synchronize anything)

require 'json'
require 'net/http'
require 'net/https'

# Put your keys here
habit_user = 
habit_token = 
todoist_token = 

hr_hd = {
  "Content-Type"=>"application/json",
  'x-api-user'=> habit_user,
  'x-api-key' => habit_token
}

if !File.file?("todo.txt")
  File.open("todo.txt", "w") do |aFile|
    aFile.puts("0")
  end
end

aFile = File.open("todo.txt", "r")
seq_no = aFile.readline
aFile.close

url = URI.parse('https://api.todoist.com/TodoistSync/v5.3/get')
post_args1 = {'api_token'=>todoist_token, 'seq_no'=>seq_no}
resp, data = Net::HTTP.post_form(url, post_args1)
jd = JSON.parse(resp.body)

jd['Items'].each do |it|
  # Checked means that you marked it as complete in Todoist
  if it['checked'] == 1
    # Adding a task is a two-stage process:
    # 1. First, add it as a to do item
    # 2. Next, Mark that item as complete
    #
    # if you just immediately mark it as complete you don't get XP

    hr_args = {
      'type' => 'todo',
      'completed' => false,
      'text' => it['content']
    }

    url = URI.parse('https://habitrpg.com:443/api/v2/user/tasks')
    http = Net::HTTP.new(url.host, url.port)
    http.use_ssl = true
    request = Net::HTTP::Post.new(url.request_uri, hr_hd)
    request.body = hr_args.to_json
    response = http.request(request)
    hr_j = JSON.parse(response.body)
    hr_id = hr_j['id']

    url = URI.parse("https://habitrpg.com:443/api/v2/user/tasks/#{hr_id}/up")
    http = Net::HTTP.new(url.host, url.port)
    http.use_ssl = true
    request = Net::HTTP::Post.new(url.request_uri, hr_hd)
    response = http.request(request)
    puts "Added #{it['content']}"
  end
end

File.open("todo.txt", "w") do |aFile|
  aFile.puts(jd['seq_no'])
end

Hi, I'm totally noob here. How can I run this script? Thanks