How to create a border + border colour field on an image
It looks like you're using a Matrix block with a field inside a block called Image. Given that information, I'd add a new field to that block called Border. You could either use a colour field, or a dropdown to set your own values. Then maybe something like this on the front end:

{% if block.image|length %}
&lt;img src="{{ block.image.one.url }}" {% if block.border|length %} class="bordered border-{{ block.border }}"{% endif %}&gt;
{% endif %}


Craft doesn't have any relation to the front end of your site intrinsically, so you could call the field whatever you like.