Francis here, so, I've never wrote or even glanced at this part of coh2.org, so.... how do i post my drawing???

mate.
Hover to your username at the top right and click "My Files". Click "Upload" and upload the picture of your drawing there. You can rename it to anything you want while you're uploading. After that, you click the name of the picture you uploaded in the list below in "My Files". Copy the link and come back here.
Create a new post then look at the top bar above the typing box. You can choose either "Insert Image" or "Insert Image with Link". The latter will allow others to click on your pic and possibly see a larger version of the pic depending on the size. It will ask you for the link of the image you want to show. Paste the link you copied earlier and hit "OK". Type anything to accompany the image you just uploaded.