There's a Snipping Tool in most versions of Windows. You can use this to take a picture of the whole screen on your computer or just a small portion. Here are some instructions - feel free to play around with it. If you want to practice, you can insert the photo in Word to see what it will look like once uploaded.
1) To access the tool:
2) Either select the Snipping Tool in the list or find it in the
Accessories folder
3) The Snipping Tool is now open. The background/screen will grey-out a little and this box will appear. Drag your cursor around the area you want to keep and save. When you let go, the tool will show you the capture.
4) To save the capture, click on the disk icon and save the capture as a JPEG file:
5) To upload the capture in the forum, follow the same steps you would to upload an image.
Note: Various editions of Windows have different editions of the Snipping Tool - newer versions have more options but the basic steps above are still the steps you'd follow. You can learn more here:
https://support.microsoft.com/...
I hope this helps!!
@Joannakat please let me know if there's something else you'd like me to add to these instructions.
Edited to enlarge screenshots