打开GIMP。 在GIMP中打开图像。 点击窗口。 选择可停靠对话框。 点击图层。 选择图像。 降低“不透明度”值。 退出“图层”窗口。 点击图像。 点击平整图像。 将项目导出为PNG文件。

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
The GIMP app icon resembles a dog-like face holding a paint brush in its mouth. GIMP may take a few minutes to open if you haven't recently opened it. Click File in the top-left corner of the window (Windows) or the screen (Mac), then click Open... in the drop-down menu, select an image to open, and click Open.  You can repeat this process for multiple photos if you want to layer the transparent image over a non-transparent one. If you open a second image in a second window, select it, press Ctr