Course
Course
If you do not have access to Photoshop you can try using an online photo editor called Photopea. There is a tutorial you can follow as well. It may be glitchy in places. Keep in mind that it is not Photoshop and it is running within a browser so your computer may have compatibility issues or run out of RAM etc. Having said that, it is a really good way of practising a lot of transferrable skills.