Go to the Google analytics's admin area and copy the code. Admin > Property > .js Tracking Info > Tracking Code
This one is more easier and neater then the above one. First get the analytics ID from your analytics code as you can see in the picture above or you can find it right next to your website name when you open your Googe anlytics.
After getting the ID go ahead and open your blogger and then go to the Settings > Other > then at the bottom you will find an emty box next to "Analytics Web Property ID" just paste your ID in the box and save it.
That's it, Enjoye!!! :)