That's a really good start!
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I suggest to resize it, make it smaller in size, for example look at the top bar, the navigation, the panel's headings - they are disproportionately big.
I think there's too much white space, especially on the left and the bottom.
Make sure you're consistent in your design, especially that "Social Media" panel, it should look like the other panels.
Overall good color scheme (grey & white) and good use of three-columns design, can be improved but overall it's good.
In the future, try to look into non-generic designs, i.e. not the traditional two/three-columns design, try thing that weren't done by others, be more creative.
Good luck