You can use your images files for make seamless texture.

In the main toolbar, click to open and choose an image file.

Now, in the Image menu, click the Make Seamless tool.

In the Make Seamless dialog box, you can adjust horizontal and vertical shift. The image is shifted and the edges are blended.

The result of the Make Seamless tool. Before and after.

Another sample of seamless texture. Before and after.