Judy Chambers

I am new to VCF and am having trouble inserting an image as background and having it come out the right size and print well. I want a chart that is 16 x 20. I need 5 generations. Setting up the chart data is no problem. What file formats work best for images? Is there any way to take an image saved as a pdf file and convert it so it can be used in the background? I know this image has been printed as a large poster from the pdf file. What image size would be needed to get a printout that large that is clear? Do I need to save it to a different format? I am just learning about using images. I hope this makes sense. Thank you, Judy