Najti i class... ikono?

Zlovdal sem template, ki ga bom preuredil in tako dobil spletno stran.

Te rumene ikone hočem spremeniti, da bo drugačen znak notri, ostajajo rumene, sam recimo namesto kompa bo ura.

Mislil sem, da je v mapi images pač rumen krogec, ki ga zbrišem in narišem kar čem in shranm ter to je to, ampak NI.

Kodo, ki mislim da "ureja" te krogce bom prilepil tukaj. Zanima me, kako "fizično" priti do teh krogcov oz. kako jih spremeniti?

<div class="row text-center">
                <div class="col-md-4">
                    <span class="fa-stack fa-4x">
                        <i class="fa fa-circle fa-stack-2x text-primary"></i>
                        <i class="fa fa-shopping-cart fa-stack-1x fa-inverse"></i>
                    </span>
                    <h4 class="service-heading">E-Commerce</h4>
                    <p class="text-muted">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Minima maxime quam architecto quo inventore harum ex magni, dicta 

impedit.</p>
                </div>
                <div class="col-md-4">
                    <span class="fa-stack fa-4x">
                        <i class="fa fa-circle fa-stack-2x text-primary"></i>
                        <i class="fa fa-laptop fa-stack-1x fa-inverse"></i>
                    </span>
                    <h4 class="service-heading">Responsive Design</h4>
                    <p class="text-muted">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Minima maxime quam architecto quo inventore harum ex magni, dicta 

impedit.</p>
                </div>
                <div class="col-md-4">
                    <span class="fa-stack fa-4x">
                        <i class="fa fa-circle fa-stack-2x text-primary"></i>
                        <i class="fa fa-lock fa-stack-1x fa-inverse"></i>
                    </span>
                    <h4 class="service-heading">Web Security</h4>
                    <p class="text-muted">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Minima maxime quam architecto quo inventore harum ex magni, dicta 

impedit.</p>
                </div>

se da naresti "costum" font awesome?