How to change the content value of iconmoon font?

I've used icomoon font on my menu. I could not change the font icon of PICTURE menu. Initially it was BLOG icon. And now I need to change it with the icon of PICTURE (CAMERA). How to change the content value of BLOG into PICTURE?

HTML PART

<nav id="menu" class="nav">                 
<ul>
<li> 
<a href="#"> <span class="icon"> <i aria-hidden="true" class="icon-home"></i> </span>
<span>Home</span>
</a>
</li>
<li> 
<a href="#"> <span class="icon"> <i aria-hidden="true" class="icon-portfolio"></i></span>
<span>About Us</span>
</a>
</li>
<li>
<a href="#"> <span class="icon"> <i aria-hidden="true" class="icon-camera"></i></span>
<span>PICTURE</span>
</a>
</li>
</ul>
</nav>

CSS PART

@font-face {
font-family: 'icomoon';
src: url('../fonts/icomoon.eot');
src: url('../fonts/icomoon.eot?#iefix') format('embedded-opentype'),
url('../fonts/icomoon.woff') format('woff'),
url('../fonts/icomoon.ttf') format('truetype'),
url('../fonts/icomoon.svg#icomoon') format('svg');
font-weight: normal;
font-style: normal;
}

@font-face {
font-family: 'icomoon';
src: url('../fonts/icomoon.svg#icomoon') format('svg');
};

.icon-camera, .icon-home, .icon-portfolio {
font-family: 'icomoon';
speak: none;
font-style: normal;
-webkit-font-smoothing: antialiased;
}

.icon-camera:before { content: "e600"; }
.icon-home:before { content: "e002"; }
.icon-portfolio:before { content: "e003";}

a, li { -webkit-tap-highlight-color: rgba(0, 0, 0, 0); }