The files you use to assemble an Adobe After Effects project are called footage items, and include video footage, still images and audio files. You import these files into the Project panel and then drag them into the After Effects timeline to build your project. You can sort and organize the files in the Project panel if you have a complicated project, and you can refresh or reload the files if you've made changes to them after you loaded them in the project.
Open After Effects. Load an existing project or click "File" and then "New Project."
Right-click the Projects panel and click "Import." Select "Multiple Files." Click a file to select it and then click "Open." Continue adding files until you have imported all files for your project. Click "Done."
Click a file or press "Ctrl" and click multiple files in the Project panel to highlight them. Click "File" and then "Reload Footage" to refresh the file.
If you reload or refresh a file in the Project panel that is no longer in the same location or has been renamed, you receive an error message and the file name changes to italics.
You can replace all instances of a file in your timeline with another file. Right-click the footage item, click “Replace Footage” and click “File.” Navigate your file system to the new file and double-click it. You can also press the “Alt” key and drag another file onto an existing footage item.