Using project files in After Effects is straightforward: you start by opening the .aep file, which automatically loads all compositions, assets, and settings exactly as the creator arranged them. If any files appear missing, use File > Replace Footage > File to relink the correct media. Once everything is connected, you can explore the main composition, adjust text, replace images or videos, and customize effects to match your style. Project files make workflows faster because you’re working from a pre-built template—just swap in your content, render, and you’re done.