...
The Amira GUI is divided into four main frames. In the image below, I've given them names that I'll refer to for the rest of this tutorial:
1. In the Pool frame, click the green 'Open Data' button. Select your current directory from the upper pull-down menu (it should be the top choice), and select the first volume (basename.rec OR basename.2Dbin2.rec). Click the 'Load' button and select 'MRC Volume' in the 'Dialog' pop-up window. Click the 'OK' button.
Pool --> Open Data --> Select Data --> MRC Volume
...