Как сделать свой стиль? Мне нужен вот такой:

.kupivkredit-button {
  position: relative;
  display: inline-block;
  width: 200px;
  height: 50px;
  *display: inline;
  *zoom: 1;
  outline: none;
  text-align: left;
  text-decoration: none;
  white-space: nowrap;
}
button.kupivkredit-button {
  margin: 0;
  padding: 2px 3px 4px;
  border: 0px none;
  outline: none;
  overflow: visible !important;
  cursor: pointer;
  background: none;
}
a.kupivkredit-button:after {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: url(about:blank);
}
.kupivkredit-button:hover .kupivkredit-button-content {
  background: #f8a416;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #fec953), color-stop(100%, #f39c0c));
  background: -webkit-linear-gradient(top, #fec953 0%, #f39c0c 100%);
  background: -moz-linear-gradient(top, #fec953 0%, #f39c0c 100%);
  background: -o-linear-gradient(top, #fec953 0%, #f39c0c 100%);
  background: -ms-linear-gradient(top, #fec953 0%, #f39c0c 100%);
  background: linear-gradient(to bottom, #fec953 0%, #f39c0c 100%);
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#fec953', endColorstr='#f39c0c', GradientType=0);
}
.kupivkredit-button:active .kupivkredit-button-content {
  box-shadow: inset 0 1px 6px #563806;
  -webkit-box-shadow: inset 0 1px 6px rgba(86, 57, 6, 0.35);
  -moz-box-shadow: inset 0 1px 6px rgba(86, 57, 6, 0.35);
  box-shadow: inset 0 1px 6px rgba(86, 57, 6, 0.35);
  background: #f3a626;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #f3a626), color-stop(100%, #f3a626));
  background: -webkit-linear-gradient(top, #f3a626 0%, #f3a626 100%);
  background: -moz-linear-gradient(top, #f3a626 0%, #f3a626 100%);
  background: -o-linear-gradient(top, #f3a626 0%, #f3a626 100%);
  background: -ms-linear-gradient(top, #f3a626 0%, #f3a626 100%);
  background: linear-gradient(to bottom, #f3a626 0%, #f3a626 100%);
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#f3a626', endColorstr='#f3a626', GradientType=0);
  line-height: 49px;
}
.kupivkredit-button-content {
  display: block;
  padding: 0;
  height: 100%;
  cursor: pointer;
  background: #f8ad30;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #fec953), color-stop(100%, #f5ac33));
  background: -webkit-linear-gradient(top, #fec953 0%, #f5ac33 100%);
  background: -moz-linear-gradient(top, #fec953 0%, #f5ac33 100%);
  background: -o-linear-gradient(top, #fec953 0%, #f5ac33 100%);
  background: -ms-linear-gradient(top, #fec953 0%, #f5ac33 100%);
  background: linear-gradient(to bottom, #fec953 0%, #f5ac33 100%);
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#fec953', endColorstr='#f5ac33', GradientType=0);
  box-shadow: 0 1px 3px #8a621f;
  -webkit-box-shadow: 0 1px 3px rgba(137, 98, 31, 0.9);
  -moz-box-shadow: 0 1px 3px rgba(137, 98, 31, 0.9);
  box-shadow: 0 1px 3px rgba(137, 98, 31, 0.9);
  -webkit-border-radius: 15px;
  -moz-border-radius: 15px;
  border-radius: 15px;
  color: #fff;
  font: 700 20px/24px 'Helvetica Neue', Arial, sans-serif;
  text-shadow: 0 1px #b1760c;
  line-height: 50px;
  text-align: center;
}
.kupivkredit-button-content > .kupivkredit-icon {
  margin: 0 5px 0 -5px;
}
.kupivkredit-icon {
  display: inline-block;
  *display: inline;
  *zoom: 1;
  width: 35px;
  height: 35px;
  vertical-align: middle;
  background: url(data:image/png;base64,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) no-repeat;
}

 я не пойму куда его вставить

возможно я неправильно выразился, я знаю как и куда вставлять, но я не могу найти стили отвечающие за кнопку Купить в кредит, эти стили необходимо изменить, какие стили отвечают за дизайн данной кнопки изначально?