Adding a search bar to the header of a child theme?

I am currently using the NewDay child theme for the responsive coupon theme. I love the theme but there is no search bar in the header like the one in the default theme. I know it is possible to add the search bar in the child themes because https://www.thecouponoasis.com/ has somehow done it. I have very little knowledge of coding so I am completely lost.

I have tried putting the code below in the header:

<form method=”get” id=”searchform” action=”<?php bloginfo(‘home’); ?>/”>
<div><input type=”text” size=”put_a_size_here” name=”s” id=”s” value=”Write your search and hit Enter” onfocus=”if(this.value==this.defaultValue)this.value=”;” onblur=”if(this.value==”)this.value=this.defaultValue;”/>
<input type=”submit” id=”searchsubmit” value=”Search” class=”btn” />
</div>
</form>

While a search bar showed up, it never found anything. Any ideas on how to do this? Would it be possible to copy some code from original non child theme and paste it in the newday theme? I see this problem has come up before on the forum with no definitive answer.