1) Click on the Gallery button (top of this page)
2) Click on Upload
3) Select Category (Screenshots or Wallpapers)
4) Create an Album (e.g. User's Work) or, if you have already created one, click on Select Album to select the album you want to add more work.
5) Make sure you are using the Full Editor and click on Choose Files
6) A browser window comes up and you can pick any file from your computer. After you pick it, click on Open on the browser window (may be different on some file browsers, but the main idea is to pick the file of the screenie you want to upload). The file is being uploaded to BB4Win.
7) Click on Review and Publish. Add title and comments.
8) Click on Finish and Publish.
9) Voilà! Thanks for posting!