Acroread (the reader) can be installed in different places.
First find where the binary actually is located.
If you have locate installed, use that (after updating).
$ locate acroread
You should get at least one hit.
If you do not have locate installed, use find:
$ find / -name acroread | grep bin
Again, you should get at least 1 hit.
Now you know where the acroread binary is located.
You do not mention which window manager you are using, so I cannot tell you how to create a button/link for your specific WM (chances are that I'm not using the one you choose. I'm using xfce/blackbox).
Hope this gets you going again.