How do i use the F keys

Question

i have a program that requires me to use f4 to open up a particular window. however when i hit f4 on my new keyboard nothing happens. the keys seem to be multi functional it has F4 on the front side of the key and on top where my finger presses it says save with a picture of a floppy disk. I cant figure out how to get it to use f4 instead of save. please help me.