In general AppImages can just started by double clicking or executing them from the terminal (./MyApp.AppImage). If you want to have them accessible from the start menu, you have to do a little bit more work.

First, move your AppImage to a suitable location. One option is to create a new directory for all your apps (e.g. an "Applications" directory in your home folder). I prefer to store them in .local/bin, as this folder is added to the $PATH variable. This allows you to use the app anywhere by calling it in a terminal. For GUI apps you most likely want to start them from the start menu of your desktop environment. For most apps, this can be achieved by following these steps.

1. Open the App
2. In a terminal call mount and look for the application name. You can use grep to filter the output. (mount | grep MyApp)
3. Open the location in your file manager. In the directory you should find:
   • an icon. This can be a PNG in the main folder. In my case (Obsidian) the icons where stored in usr/share/icons/hicolor
   • a "desktop configuration file". It's content should look similar to this:

   [Desktop Entry]
   Name=Obsidian
   Exec=AppRun --no-sandbox %U
   Terminal=false
   Type=Application
   Icon=obsidian
   StartupWMClass=obsidian
   X-AppImage-Version=0.13.19
   Comment=Obsidian
   MimeType=x-scheme-handler/obsidian;
   Categories=Office;
   

4. Copy the icon into .local/share/icons. If you find a hicolor folder in the app directory, copy the entire folder over. (use Ctrl+H to show hidden files)
5. Copy the desktop configuration file into the .local/share/applications/ directory in your home folder.
6. Edit the copied desktop file.
   • Replace the app name in the Exec= (and TryExec=) statement with the full path to the AppImage. In the example file above: Exec=~/.local/bin/MyApp