This question is very unspecific, but I will anyway try to answer.
I will just assume that you want to start with shooting wide-angle photos, e.g. the milky way.
What you need
- A camera and lens (obviously)
- A tripod: In order to shoot the long exposures needed to capture the faint light of stars, you need something to put your camera on, to avoid camera shake. If you don't have a tripod, you can try using anything that keeps your camera sturdy.
- (Optional) a remote trigger. This allows you to take a photo without physically touching the camera. Again, this avoids camera shake. You can also use the camera's built-in timer or use, if supported, a mobile app to take a photo.
Which settings?
- Aperture: Stars are very faint, so you want to open up the Aperture to f/3.5. If you feel that it is not sharp enough (especially at the edges), try to stop down a bit
- Shutter speed: Since earth rotates, you can only leave the shutter open for a while before the earth's rotation causes the stars to trail. A commonly used rule to determine the maximum shutter speed for a given focal lenght is the so-called "rule of 600". Basically it says that Shutter speed = 600/focal lenght. As the D5600 has an APS-C, you have to multiply your focal lenght by 1.5. I found the 600 rule to be not working so good and chose to use the 300 rule instead. According to this, you can leave the shutter open for about 11 seconds at 18mm (Tests with my Nikon d5300, which is very similar, confirmed that you cannot go much above 11-13 seconds before the stars start trailing).
You can also just try how long you can leave the shutter open before the stars trail, but the 300 rule gives you a good starting point.
- ISO: There is no "rule" for ISO. Try starting at about 800-1000 and if you feel that your image is too dark, increase ISO. However, you do not want to go too high, as noise increases (For my d5300, I like not to go over ISO 3200 - 6400; at this point, Noise is still acceptable
Some other things
- Shoot in Raw. Astrophotography needs post-processing. This for example also allows you not having to care ybout white balance, as you can change it later
- Stacking: You can shoot multiple images and stack them together (Sequator is a free Stacking software for Windows) to reduce noise. This is especially useful on crop-sensor cameras which usually do not perform too god at higher ISO.
Conclusion
You can shoot Astrophotos with your camera and kit lens. However, you are limited by
- The ISO performance of your camera
- The Aperture of your lens - Dedicated Astrophotography lenses usually offer an aperture of at least 2.8 to let more light in
- The focal lenghst of your lens - Many Astrophotography lenses are more on the wide end of the lens spectrum, e.g. 14mm. This allows for longer exposures and thus lower ISO which means less noise
The kit lens is however a good starting point to find out whether you like astrophotography and learn the basics.
I hope this somewhat helps!