The first step is to sign in to your AssetPot account as an admin user. You can sign in here
Once you have logged in, you will be greated by all of the assets in your AssetPot. Click on the small cog symbol below the asset you want to edit.
You will appear at a page where you can edit the title, category, description and tags of the asset. You can even replace the image with another one by clicking on the 'select files' box