Colours that are close to each other on the colour wheel are considered harmonious. They are technically called Analogous Colours.
For my photograph of Gunn Beach near Darwin, above, I have created a photograph with an Analogous Colour scheme. The Purples, Reds and Oranges are all fairly close to each other on the colour wheel.
I have used the analysis tool at Adobe Colour https://color.adobe.com/create to have a look at the colours on the colour wheel.
You can create your own colour schemes using the tools and the colour wheel at Adobe Colour https://color.adobe.com/create
I personally prefer to use a physical colour wheel. When I was younger I had one printed out and had it on the wall next to my drawing desk. You can download this one and print it for home. Download Real Colour Wheel. There are many colour wheels, the one bellow is fantastic for artists because it works on how our eyes and brain see colour. You can read more about this colour wheel at the http://www.realcolorwheel.com/colorwheel.htm
You may find it easier to construct your coloured photograph at home on a table. For example we had to paint lemons in a yellow bowl, on a yellow tablecloth at art school.
You may wish to play with your colours in software to create your analogous colour composition. You may be lucky enough to find it in nature as I have done with my example.
Post a few different ones, and try some different analogous colour combinations.