If you are using an outdoor UHF antenna, you should be receiving very good signal. The amplifier is probably not needed. You can verify this by doing a manual scan, channel by channel, for chans 27, 29, 31, 38 and the latest test transmission on chan 33. Note the signal intensity and signal quality for the different channels with and without amplifier.
Amplifier can increase signal strenght but at the expense of signal quality. This is because the amplifier itself adds noises (=<3db according to specs) to the amplified signal.
As pointed out by AnDyLe0, just plug in a usb hdd and you are on the way. Thumb drive, card reader with SD card or equivalent also can.
However, if you are still stumped after an external drive is attached... the quick answer is the "pause" button on the remote will start the time shift function. To resume, press the "play" button.