First of all I am glad that you are using a bit of a longer wire than that of the whip antenna which is limited to say the least but does perform when the propagation is at its best.
HF works a little different to that of VHF and above which is as a general guide line of sight whereas HF signals bounce of the charged ionosphere and they can then return to earth and be either absorbed or reflected back up to the ionosphere many times and this is where you get your propagation effect to summarise it. Now we find that night time is the best time for reception as the ionosphere has been charged so to speak throughout the day time and this acts like the mirror we need where as in the daytime a lot of the signals are briefly propagated or absorbed by the atmosphere. Now the finer details is that certain bands will allow international contacts throughout the day dependant upon season and current solar state but that is enough of that as this will become a lecture and the internet is full of this information.
First thing first is get the antenna in a high as possible horizontal position away from any mains bourne electronic noise sources (easier said than done) then check that you have the switch on the left side set to DX as this is a form of attenuator.
Go to sites such as this for radio broadcast listings: http://www.shortwaveschedule.com/index.php?now=true
enter your details such as GPS location and then fine line it offer only English languages unless your fluent in others, you may not be able to hear all those stations of course. Look for CRI (China Radio International) as they offer one of the most consistent signals on the airwaves. Try from the lowest frequencies and work up until you find activity on the air. Most SWL will be in AM of course and Volmet stations you mention will use USB.
Also check out that there is no active solar flares or solar winds as this basically strips the ionosphere of its reflective properties and makes HF sound deaf so check out: http://www.spaceweather.com/
at this time we are on a KP3 which is not good for HF reception, located on the left hand panel of the above website.