To manually georeference an aerial map in QGIS, you'll need a target dataset to reference against. This is where OpenLayers comes in handy.
1. In QGIS, go to Plugins > Manage and Install Plugins.
2. Search for OpenLayers in the search bar of the new dialogue window. Select Install.
3. Go to Web > OpenLayers plugin > Google Maps > Google Satellite. You should now see the familiar google maps world view on the main window (If not, navigate to the Layers Panel, and check the checkbox to add it).
4. To make the reference projection match your Maps Made Easy GeoTiff, click the in the bottom right corner of the window. (your’s may have a different number to begin with).
5a. Search WGS 84 / Pseudo Mercator in the search bar of the new "Project Properties" window.
5b. Make sure "Enable 'on the fly' CRS transformation" is check marked. Otherwise, you won't be able to project your aerial maps accurately. Hit OK.