Fitting a square image on a latte mug

I am with dog rescue and I just purchased some latte mugs to put designs on for Christmas.  Because of the shape of the mugs a simple square design, which is what I'm working with,  won't work.  The design I have is a bitmap and I need to change the shape so it fits in the template of the latte mug.  I can't seem to get the shape tool to help me with this.  I need to get this figured out so we can sell these for Christmas and I'm running out of time.  I have tried to figure it out myself but to no avail.  (Corel can't help me due to the version I am using and I can't afford to upgrade but could download the trial version if that would help)  I just don't know if I can reshape a jpeg or bmp in either version or how to make this work.  Hellllppppp