like in boardmaker ?
i am on windows
Photoshop is a very complex program. If you are trying to learn how to use it, you should look for tutorials on the web. Follow people's examples of how they made pictures to learn the techniques before you try to do your own. I'd need to know more about what you want to do before I could give help (and it's a few years since I've used Photoshop).
Here is a site with links to other sites where you can download pecs symbols other people have made:
https://sites.google.com/site/speaking4autism/information/free-picture-symbol-resources
may not be helpful but widget do 'writing with symbols' an you can have a monthly subscription called 'symwriter' for under £3 . I have not used this but have used writing with symbols until hubby accidentally deleted it off computer. with that you could just add your own photos into a word document which created the symbols at the same time as you typed. They used to have one that talked as you type too, not sure if still does this.