How can I get the right tension on my Frister Rossmann Cub 3?

I have a Frister Rossmann cub 3 sewing machine that hasn't been used for a while. I set it up to test and after realising that there is hardly any tension in the stitching from the needle and the bobbin I checked the needle to see if it was picking up the thread from the bobbin. It does but then still does not stitch. I don't have a manual and I am unsure as to what tension setting to start on first to work from to get the right tension. Mechanically it seems fine and is working well.