There are many alternative applications released for Windows operating systems. From the most known ones I can recommend you (from complex to simple) Photoshop, Paint.NET, Picasa, Photoscape, and IrfanView. As a personal recommendation, I would choose Picasa or Paint.NET as a medium difficulty and complexity when it comes to image editing. Picasa, however, can be both complex and simple. You can try each one of them to see which one suits you best for your needs.