Welcome to the forum.
I agree with Hugh. Also I notice that the flash was used and guess this is because of the night time mode that you selected? The flash wouldn't really have added anything to this image because of the distance from the subject and the fact that the monument already has lighting.
A tripod really would have been a must for this image (or at least some sort of support, a camera bag or rolled jumper perhaps). Try taking it on apperture priority and let the camera decide your shutter speed. I'm guessing at ISO100 you'll be looking at about 2 (or upwards depending on the apperture value), hence the need for a support. If it's windy though you will still get some shake.
I've not seen the monument at night but visited not so long ago during a busy Sunday. There were people everywhere and I struggled to find an unusual vantage point. Knowing the monument I really like this image though, you have choosen a good time for taking it and the vantage point works quite well at night, far more so than it would have in the day.
I see that you are local - I'm in Durham. If you need any further explanation or help just ask!
