It is important to submit your files as a print-ready document, so either as a .pdf, .jpg or .tiff.
No other document type is suitable, so Word (.doc) or Powerpoint (.ppt) files are not suitable for professional printing.
Programs such as Adobe InDesign, Adobe Illustrator and Adobe Photoshop are the best for creating the desired layout of your print.
If you don't have access to these programs, there are many other programs you can use to create a file. For example Scribus (as a free alternative for InDesign) or GIMP (as a free alternative for Photoshop).