Nice camera, I have a 5600 so yours works almost exactly the same, use it in manual mode as you will get better pics eventually.
Use the 18 - 55 to practice and remember that if something is too close you will never get it in focus.
I use the screen for focusing, aim for what you want to focus on and press the button on the right, below the toggle thing with a picture of a magnifying glass with a plus in it, press that and you will zoom in on your chosen focal point, I let the auto focus get there or there abouts, zoom in and manually tweak the focus.
This is about 10 inches from the glass with my 40 mm macro.
ISO 640 Good general setting.
F5.6
1 / 160
Right mouth focal point then left.
Have a play but pick a coral as your test piece and play,
focus on one area and see what you come up with, settings can be tweaked to give more depth of field ie more of the image in focus but you need to get a starting point.
Tip of the lens square on level touching the glass and camera horizontal!
(If that lens is tip focus and not internal you will struggle with it touching the glass, pull back 1/4 inch, auto focus, place the lens back on the glass and manually re focus or just manual focus anyway!)
Feel free to post pics here and remember different lights will require a different white balance, if you have the camera ready to take a pic go into the menu, top left on the back you can scroll through them and see what you are likely to get as an end result.
Good luck. :)