This is same thing as a Janome Memory Craft 6000 (called New Home in UK I think) so why not buy a manual for it, they usually run to 100 pages and are well worth having to best maximise your use of the machine and prolong its life by properly maintaining the machine.
Here is link to a photocopy of this manual on www.sewingpartsonline.com
Or you can buy a copy on this website
The top loading bobbin will have a tension spring on the side that you need to "click" the bobbin thread into so it is tensioned. There is usually a little crack that the thread goes down into, its a case of holding the thread tail with your right hand, placing a finger tip from your left hand onto the bobbin to hold it still, then press down on the thread tail with another figer so it clicks in
to the tension device.
Then place cover plate back over the bobbin leaving the thread tail hanging out and do the usual "lower the needle" down then back up to draw the bobbin thread up to the needle plate.
Top threading up should be fairly obvious, always do with the pressure foot raised and pay attention to the tension dial and the thread take up lever, all machines have these two points to manipulate the thread and then some thread guides to take the thread down to the needle. I just can't find a threading diagram for this machine online to refer to but Janomes are very similar so if you go to http://www.sewusa.com/Threading_Diagrams/Threading_Pages/New_Home_Threading_Diagrams/New_home_2022_Threading_Diagram.htm
and take a look this may get you going.
Hope this helps you out with the 6000, 4 thumbs up if so.
PS, I always hand hem trousers myself, I just overlock the raw edge first for neatness. If there is hardly any hem allowance, then I will stitch on a piece of bias binding to cover the raw edge, then turn this up and hand sew it.