How to process the files using .tar.gz files in script

Hi,

I have some file in /users/xyz directoty with .tar.gz extension. i need to find these files and if found in need to run other commands. I now the command for finding files,but how to put if condition ?please help me

Thanks

#!/usr/bin/ksh

if [ -f /users/xyz/*.tar.gz ];
then
<do something
fi

Thanks for your reply. Now i am trying to run the following script,
Script name is TestScript.sh#!/bin/sh

if [ -f /users/home/conmjr/*.txt];

then

cd /users/back_scan

fi

But , i am getting the foolowing error

./TestScript.sh: test: ] missing

is there worng in my script

Put a space between the last character and the close bracket ]