Pro Tip: Anything "Blue" is not dimensioned which means it can be moved around. Anything "Black" is dimensioned which mean is has a size. Once the whole sketch is Black it is "Fully Dimensioned." This means it's "locked" into place.
Right Click on the top level assembly in the model browser and choose Export. Options: f3d, iges, step, sat, smt
STL Export
Right Click on the top level assembly or any component or any body in the model browser and choose "Save as STL".
File > Export will give all possible export options. Some require the assistance of the cloud.
Click "Open on the web" globe with eye icon in the left sidebar (data panel). This will open your Autodesk proejct workspace in the browser. Locate the file you wish to export and click the small arrow to chose file type.