Here is a little guide on how to get the work done 
NOTE: An indicator can be of 2 format (extensions), .MQ4 and .EX4. MQ4 is the source code, and EX4 is the compiled version of the code.
Step By Step
1) Download/Copy/Save the MQ4/EX4 file into your
C:\Program Files\MetaTrader 4\experts\indicators folder
2) Close your MetaTrader application (assuming it's currently open ... Ignore this if the application hasn't been launched)
3) Launch your MetaTrader application
4) On the left hand side, look for the "
Navigator" window
5) Under the "
Common" tab, look into the "
Custom Indicators" directory
6) Locate the indicator which you have just downloaded into the folder stated in Step 1
7) Drag (Click and drag) the indicator onto the chart
8) Voila... done