Including phone number field

I attempted to follow the steps provided in another thread (now closed) to add a phone number field, but it’s not working for me.

The provided code is below:
<label for=”tel” class=”screenread”>[text for screenreaders to read here]</label>

<input type=”tel” value=”default value for tel input” id=”enews-tel” onfocus=”if ( this.value == ‘default value for tel input’) { this.value = ”; }” onblur=”if ( this.value == ” ) { this.value = ‘default value for tel input’; }” name=”WHATEVER FORM NAME IS REQUIRED BY YOUR MAILING SERVICE” />

I’m using Mailchimp. Am I just to replace the text in CAPS and if so, what “name” is this referencing and where would I find it? Sorry but WordPress newbie here.

Thanks.