Translate First Namen and Last Name in contact form

Hi, 
I'm using square space for the first time and I have never coded before so I hope you guys can help me.  I'm trying to translate the hard coded labels in the contact form on our web page https://padelakersberga.com/kontakt-1

I tried with this code, but it didnt work:

<script>  
  if (document.querySelector("#name-yui_3_17_2_1_1553888888520_3744")) {
    document.querySelector('.field-element field-control[name="fname"]').placeholder = 'Förnamn';
    document.querySelector('.field-element field-control[name="lname"]').placeholder = 'Efternamn';    
  }
</script>

Maybe I'm way off here, the code could be totally wrong, but I found some similar code while searching for answers so this is what I came up with. 

BR
Ted

Hello @paul2009,

I have placed this version code

<script>  
  if (document.querySelector("#name-yui_3_17_2_1_1559593002966_3555")) {
    document.querySelector('.field.first-name .caption .caption-text').innerText = 'First name';
    document.querySelector('.field.last-name .caption .caption-text').innerText = 'Last name'; 
  }
</script>

in the PAGE HEADER CODE INJECTION of a certain page in order to only change it there, but nothing happened. Then I went on and put it onto the global footer code injection and then it change BUT unfortunately for all pages. I would like to have it only on my English contanct form.

Do you know how I can accomplish that? I am working on stelviopartners.com

thank you in advance for any kind of help, cris

33 minutes ago, Xbal said:

I would like to have it only on my English contact form. Do you know how I can accomplish that?

There are a number of ways to do this. The simplest way should be to add a Code Block to this page, placing it below the Form Block. Add the code to the Code Block instead. 

Coolio Julio! that easy! now I am speechless and I feel a bit like: how come I didn't come up with this solution....thank you very much @paul2009

Which are the other ways if I may ask?

46 minutes ago, Xbal said:

Which are the other ways if I may ask?

You can limit to the page by checking the collection ID or the page URL slug.