How to use the neewer tt560 on my Nikon 5100?

For some reason i can't get it to work with my nikon. I Put the flash, on but when i go on to take pictures, the built in flash pop up. Ok I'm not a camera person, so help.

It seems that the external flash, the TT560 is NOT a TTL flash.

For under $50, you can't expect much from such a flash when a good used Nikon SB600 costs around $200

Here are the modes it has as well as its features.

1. M Mode

Press the MODE key to M Mode. In this mode, you can set TT560 On to your camera hot shoe or speedlite trigger hot shoe to trigger the flash unit. When shooting, adjust the flash power and press the camera shutter, the flash light will flash under the camera synchronous signal?

2. S1 Mode

(1) Press the MODE key to S1 Mode. The Mode is applicable for slave flash in order to create many lighting effects. It is respectively applicable for manual flash environment.

(2) When the flash is S1 mode, it will fire synchronously when the master flash fires, comparable with the effect by the use of radio trigger.

3. S2 Mode

Press the MODE key to S2 Mode. The mode is applicable for slave flash in order to create many lighting effects. It is respectively applicable for TTL flash environment. The flash unit won't flash synchronously with the first flash but the second flash from the master flash?

4. Power-saving Function

(1) To save battery power, the flash will enter stand-by state in about 30 minutes of idle use. Press any button to wake it up.

(2) In S1/S2 mode, the flash will enter stand-by state in about 60 minutes of idle use. Press any button to wake it up.(3) In Power-saving mode, the charging indicator flickers in every 3 seconds. Other Indicators are turned off.

5. Protection Function

(1) Protection in continuous flashes

(2) Systematic over-temperature protection

Specifications:

Guide Number:38 ( ISO 100 )

Flash Mode: M, S1, S2

Vertical Rotation Angle:0~90 degrees

Horizontal Rotation Angle: 0~270 degrees

Power: 4xAAsize batteries ( Alkaline or Ni-MH are usable )

Lighting Times: 100-1500 times ( AA alkaline batteries used )

Recycle Time: approx 0.5-5.5s ( AA alkaline batteries used )

Light Quantity Output Control: with 1/8 - stop increment

Color Temperature: 5600K

Flash Duration:1/800s~1/2000s

If this flash does not have TTL communication with the camera, then the camera does not know it is there. Automated or semi-automated camera modes will not work well with it. To use it, you need to set your camera to M mode.
Do not use shutter speeds faster than your x-sync limit of 1/200th second. Otherwise, part of your frame will be dark. The Nikon brand flash's TTL communication with the camera body would normally tell it to set this limit even in M mode.