1. Visit the following link to going to Google Analytics.

https://www.google.com/analytics/#?modal_active=none

Note: If you have a Google Account and You are not logged in, click Sign in as shown in the following image 

2.If you do not have an account on Google, you should create an account at the beginning by the following link

https://accounts.google.com/signup/v2/webcreateaccount?hl=en&flowName=GlifWebSignIn&flowEntry=SignUp

Once you're signed in to your Google Account,,,

3. Click Access Google Analytics. 

4. Fill in your account name, website name (your store) ,... then Select industry category and reporting time zone for Reports preparation.

5. Within Data Sharing Options, check the boxes next to the options you want. Then Of the Google Analytics Terms of agreement, You can click OK.

6. Then you can copy the tracking code and place it in the custom code tap at your store. Go to the control panel of your store  then click on the settings then advanced settings then click on the custom code and then put the code in the header Scripts

Next pictures to show you where to get the code from your account at Google Analytics. Also, a picture of the shape of a control panel of your Google Analytics account  and know how many visitors to your store