This is a question that comes up quite often.
​
Below you can check a quick video, which hopefully explains it better.
​

We took Open Sans Condensed as an example. First step is to take the code from the google font site, if the font is not yet present in your shop. (if it is, please skip this step)

After that you make changes directly in the HTML (see video). 

Once completed, It would look like this:

I hope this helps. 😸