I got less quality video when I uploaded it on Youtube I recorded a video using Camtasia software trial version. I produced the video in MP4 HD. The video quality is very good when I play it on my desktop. When I uploaded the video to Youtube, the video on Youtube had less quality than it has at my desktop. 

So can you help me have the very good quality (supoorts HD) at Youtube or at least having the same quality as it has at my desktop?

Thank you
It's impossible to maintain the original quality when you upload a video to youtube since youtube reencodes all videos. For a detailed explanation of why it does that, check my answer here. To minimise quality loss, export your video with a high bitrate.