When you cropped this, you should have cropped by pixel size, not by physical size. What I mean by that is if you wanted a shot that is 6 x 4" on here, you should have sized it at 432pixels x 288pixels. As your monitor (assuming Windows not a Mac) is roughly 72 dots per inch, that will show at that size.
If you took a high res photo (300dpi) and cropped it to 6x4" but still at 300 dpi, it will actually be 1800 pixels by 1200 pixels. This will display on a computer screen as huge!
In this case I note you have actually saved it as 1000 x 667pixels. If you divide those by 72, you will find it displays as 13.88" x 9.26", a lot larger than you ntended and clearly too large for the subject here which is therefore looking over-enlarged.
I hope that hasn't confused you, suffice to summarise by saying when resizing to display on the computer/internet, think ONLY about the size in pixels as this is how a computer displays images.
In this case, I think had you displayed this photo a lot smaller, it would look sharper than it does on here. Worth having a look at your original again and seeing if you can produce something a bit sharper. Obviously if the original is not sharp then you can't make it sharp now but if the original is better, you could show it on here closer to its original quality
Hope that helps,
Rob