如何限制某人可以在职位发布表格中输入的字母或字符数量？

I am running a job board and individuals can post jobs. On my Post a job page, the title where the user enters in the title of a job he/she is posting (ex. warehouse worker) does not have a max length to limit the amount of characters or letters they use.

In result, the words run across the page and over laps other content on that page. How can I fix this?

The guy who created this job board gave me this code to fix it, but I have no idea in what file to place it in. I've been given very limited information

add_filter("wpjb_form_init_job", "my_wpjb_form_init_job");
function my_wpjb_form_init_job($form) {
    $form->getElement("job_title")->addValidator(new Daq_Validate_StringLength(1, 80));
    return $form;
}

<input type="text" maxlength="15" id="textfield" name="textfield"  />  //you can put any length says 10,15.etc

Try using the <input type="text" name="customName" maxlength="customLength" />. It is widely supported and is already included in the HTML 4.1 standard. People may blame me for referring to w3schools, but there you might get more information about it, e.g. the default length of 524288 characters.

EDIT: You should not make those input fields overlap. Already with quite simple techniques, e.g. the display:table property, you can avoid that.