It appears that there are several issues.
Firstly I cannot see your image.
Please tell me what camera and lens(es) you are using – it occurs to me that you have a Cano DSLR, but confirming the specifics will be helpful
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There could be two issues here. Firstly the street lights might be “too bright” because the general scene is “too dark” in which case it is probable that your camera’s meter is being confused by the very bright lights in the scene. There are several remedies for this, the easiest I have found for a novice when shooting a STATIC SCENE is to make an exposure bracket: that means you take the first image as per the Camera’s indicated exposure and then shot maybe four more each at plus and minus 1 and 2 stops under and over the suggested exposure. You can use EXPOSURE COMPENSATION if you want to use the camera in an AUTOMATIC MODE (such as Av Mode) -OR – you can use MANUAL MODE and just change the shutter speed or aperture or ISO or a combination to make the bracket of five shots. Following this procedure at first should better allow you to learn the nuances of the METERING MODES of your camera. The camera’s Light Meter controls the EXPOSURE when you are using any of the automatic camera modes (such a “Aperture Priority Mode”)
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Lowering the F/number to 18 and at the same time INCREASING the ISO will INCREASE the EXPOSURE of the scene. Obviously then the lights will appear brighter.
If you want to DECREASE the exposure of scene (and the lights), then (as the lens is already stopped down to a small aperture and the ISO is very low) you should INCREASE the shutter speed: an increase of one stop would be setting the shutter speed to 10 seconds; two stops would be setting the shutter speed to 5 seconds. Note that this will DECREASE the exposure of the street lights, but it will also make the WHOLE SCENE in your image darker.
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The “Star Effect” on the street lights is because of the SMALL APERTURE that you are using. Using a larger aperture (smaller F/number) will reduce that effect.
I think that one of the main concerns that you are having is capturing to the very large DYNAMIC RANGE of a night street scene. The Street Lights are very bright and the general street scene is relatively dark. You need to think through what is in actually the shot. For example here the photographer moved in quite close such that the very bright lights (top LH corner) were minimal in the shot:
“Christmas Eve”
And if bright lights have to appear in the shot then you need to think through how they will be effective and sometimes the starbust can look quite nice:
“Laying Pipes”
Or simply just make sure that no street lights appear in the shot, or the lights which do appear in shot are far away and very much out of focus because of a very shallow DEPTH OF FIELD created because of using a very large aperture, which is usually quite easy for street portraiture:
“Tourists Capture Nightscape”
WW