Some of my products will go on sale. How should I go about adding a new price, and styling it so that it is red and bold?

Under the products tab, upon creating your product you may add the original price and the sales price under the “Price” and “Sale Price” field. If your product has already been created, click on the product on sale on your Products tab. Then, add the price under the “Sale Price” field. If you want to change the color of the sale price, then go under Catalogues > Your Catalogue > Custom CSS, and change the values of the following class:
.amount {color: red;}