book cover pdf

I am a small low budget publisher who needs are small project creating a pdf. I have the exact dimensions of a book cover and the cover already designed and I need to place the images into the pdf. I do not own adobe or other pdf tools that one can do this as most of my covers are designed online by software..... This is a specialty size so I need this done.... ## Deliverables This work needs to be precise, the clear dimensions are stated on the pdf.