Next to the File Name, click the button that says Upload.
You'll be presented with a dialogue box that prompts you to choose a file from your hard drive. Choose the file you wish the replace the current file, and just like that, the old goes out, and the new comes in. The replacement tag in the backend of your custom website ought to be updated automatically for congruency. In the chance that it's not, simply repeat the steps above: go to the page in which the media is downloaded from, and insert the file into the backend of that page.
When dealing with the behind-the-scenes of custom websites, things can get tricky. However, there's almost always a simple solution. If you find yourself struggling with the mechanics of your HDM custom website, please feel free to Call or Contact Us for more information. We're always here to help you get the most of these fantastic resources.