There are a number of ways this can be achieved, it maybe worth asking the developers how they intend the file to be run.
You could install SQL Server Management Studio on your own PC then connect remotely to your database and use the Tools in SQL Server Management Studio to execute the SQL file.
Another alternative is to use the Tools available in your Control Panel. Next to the name of your SQL Server database you will find a 'Browse Database' link this will take you to the myLittleAdmin Tool, from where under the 'Tools' menu you will find a 'New Query' tool. you can then copy and paste the code from your admin.sql file to the 'New Query' form and hit the submit button to execute the code.
If you are still stuck create a support ticket from your Client Area account and attach your admin.sql file and we can look at executing it for you.