After completing an embroidery panel it can be tricky centralising it. This is an easy way to do it. This is the back of an A4 pad but any card will do. Draw lines around the edge then cut out the centre.
Cut 2 corners as shown
You will now have 2 pieces of card to experiment with. Move them around until your design looks balanced within the frame. Mark a dot in each corner with a Trickmarker ( fading fabric marker pen ) then remove card. Keep the card frame for future use.