Edit in JSFiddle

nav {
    text-align: center;
}

ul {
    display: inline-block;
    text-align: center;
    padding: 10px;
    background: rgba(0,0,255,.5);
}

li {
    display: inline-block;
    padding: 10px;
    background: rgba(255,0,0,.5);
}

<nav>
    <ul>
        <li>Foros</li>
        <li>del</li>
        <li>web</li>
    </ul>
</nav>