To Fast Forward use the key
To Rewind use the key
Just keep it pressed to reach the desired time you want.

But I guess you wanted a menu option like "Go To.." to enter the time, this is not possible.
There are no bookmarks unfortunately, but there is one way to keep one track bookmarked.
If you open the file from the File Manager (say a Podcast), then you can start listening to it then you can go to the Music player (using the access key) and play another song. When you hit the access key again it goes back to your podcast and it's still in the same spot where you left it.
Hope this makes sense.