Here are some graphics programs you may find useful. Picmonkey and Canva are free.
ArtRage and Photoshop are not free but I wanted to share them with you as that is what I use every day in my own work.
*the image below is an affiliate link meaning if you purchase from this link I will receive a percentage of the sale. It does not raise the cost for you. You probably know how affiliate links work but by law, I have to tell you all of that.