I haven't used PSP but I think this will apply.
Mask carefully round the football in its original image. Edit | Copy the masked football.
Now open a new file and put in your canvas background. Then Paste the image of the football.
The excitement comes in making a believable football and arranging and sizing it in the new file.
It is usual to do something like 'combine all objects' before being able to print or save the file.