First, select a card design template you like. By clicking/tapping on it you will come to the page where you can edit your card.
In the design template, there are already pre-defined places for adding photos and edit text. If you click/tap on a text element and you are not able to edit it then it is a part of the design template and can't be changed (not by us either).
You can easily add photos to your design by clicking/tapping on the photo icon. You can move text and photos around to align them so it looks like you want.
You can change the font style, size, color, and alignment to find the perfect expression for your card.