In one sentence, describe what the following article is about:

You can load ROMs using the file menu. The Options menu will let you set your video, sound, and controller configurations. In the Options menu, select Configure Input. This will let you set what key on the keyboard is assigned to what controller function. You can also setup a PC game controller to act as an N64 controller. When a ROM is loaded into the browser, you can double-click it to start playing. If the ROM is a valid file, it should begin playing. Take note of how well or poorly it runs. Make settings to adjust the playback of the ROM. In the settings you can adjust resolution, anti-aliasing, and more. Lowering the resolution may increase performance at the expense of visual clarity. Anti-aliasing will smooth out the images, but will lead to worse performance on older systems. Mess around with the advanced settings to find a configuration that runs best on your machine. If you need to, you can reset the settings to default.
Learn your way around the program. Configure your inputs. Play a ROM. Adjust your video settings.