Thankyou for your help Canary Boy, you have solved my problem.
The series of steps I had followed were: (i) blank slide (ii) right click and select background (iii) select "fill effects" (iv) "picture" then "select picture" and then "insert" (v) then "OK" and "Apply". This method however only lets me place one picture on a slide.
Thanks again.
Cheers.
Henry