sorry asking this here, but how do i report bugs for 1.3.x and where is this version, i'm a bit confused

1.3.x is the development version and not released (also no alpha or beta versions available).
The source code of this version can be downloaded from the master branch of our source repository at https://github.com/mantisbt/mantisbt

The better places to ask such kind of questions are the forums, the mantisbt-help mailing list or IRC (refer to http://www.mantisbt.org/support.php for links and further details).