Simply unzip the file. You would find three files. Copy these files to directory of Tally 4.5.
Now run the utility and convert the companies one by one. After converting all companies you would see different folders are created . Copy these folders to the directory where your Tally 7.2 is installed. Open Tally and rewrite the companies you want to open in Tally7.2. Wollah !!! the process is complete.
Before migrating data make sure to take backups of files. so that in case of data corruption you can recover it.