How to put variables in Vue

i'm learning vue and i have small problem.

I've created code, which receive some informations from webserwer (via socket) and this code works fine.

But i would like to do very simple thing - display info as variable in HTML and i have problem with it.

My code is:

    export default {
  components: {
    BCard,
    BButton,
  },
  data() {
    return {
      connection: null,
      json: {
        cmd: 'start',
        width: 1024,
        height: 800,
        url: 'https://www.google.com',
        token: '',
        service_id: 1,
        thumbnail_width: 100,
        thumbnail_height: 100,
      },
    }
  },
  created() {
    console.log('Starting Connection to WebSocket')
    this.connection = new WebSocket('ws://127.0.0.1:8080/')
    // this.connection = new WebSocket('ws://echo.websocket.org')
    this.connection.onopen = function (event) {
      console.log(event)
      console.log('Success')
    }
    this.connection.onmessage = webSocketOnMSG
  },
  methods: {
    sendMessage(message) {
      console.log(this.connection)
      console.log(message)
      console.log(JSON.stringify(message))
      const dat = this.connection.send(JSON.stringify(message))
      console.log('TT', dat)
    },
    drawItem() {
      const img = document.createElement('img')
      const canvas = document.getElementById('canvasId')
      img.src = 'http://image...'
      img.onload = function (a) {
        const h = a.target.height
        const w = a.target.width
        const c = canvas.getContext('2d')
        canvas.width = w
        canvas.height = h
        c.drawImage(img, 0, 0)
        document.getElementById('draw-image-test').appendChild(canvas)
      }
    },
    webSocketOnMSG(msg) {
      console.log(msg)
    },
  },
}

and i would like to add code like this:

data: {
xposition: 'xpos',
yposition: 'ypos'
}

but when i'm adding it to created earlier data() i have error, so this doesn't work:

data() {
xposition: 'xpos',
yposition: 'ypos',
        return {...}
}

where should i add code to replace variables {{xposition}} and {{yposition}} in HMTL?