Open your JPEG image in the original application, such as a browser (like Internet Explorer or Mozilla Firefox) or Word processing document.
Position your cursor directly in front of the image, at the bottom. Left-click and hold the cursor at that spot.
Drag your mouse to the right until the JPEG is completely selected. You should see the image highlighted in blue (or another color, depending on your computer's settings). You may also be able to right-click the image and select "Copy Image" or similar, though this isn't always a reliable method of copying JPEGs.
Press "CTRL + C" (copy) on your keyboard. You can also go to the main menu of your program and choose "Edit" or similar, then select "Copy" from the list of options.
Go to the file into which you want to paste the JPEG. Place your cursor in the area where you want the JPEG to be positioned. Press "CTRL+V" (paste) or select "Paste" from the "Edit" menu to deposit the JPEG in its new location.