Sql 2012 log file huge

Exactly. Full Recovery Mode requires to perform DB and Transaction Log backups. Usually you perform the log backup more often (say once every 4 hours), while the DB backup is once a day or even less often. It doesn't matter whether the DB backup is differential or full.

I did both a full backup and also a trans log backup and the size is still the same.

The transaction log backup in and of itself won't shrink the log file - it just enables the space to be reused.  If you had never done a log backup before and the log file had grown large, extra steps need to be taken to shrink the logfile and then regrow in a controlled manner to a better size.

The two blog posts I listed above cover this in great detail and I don't want to steal Kimberly's work by replicating it here.   Have a read of those two posts and come back here with any other questions.

It's important to understand the impact of large numbers of VLF's brought about by incorrect sizing of your transaction log through autogrow, the impact autogrow can have on performance as well as the proper steps to shrink the transaction log back to a reasonable size.