I know Photoshop is the most important software to edit any kinds of images. is that right?
Not really. I use a program called Paint.net available at https://www.getpaint.net (https://www.getpaint.net), it functions a lot like photoshop. There's a bunch of plugins to make it do different things. Also another popular tool is Gimp at https://www.gimp.org/ (https://www.gimp.org/).