The method for scanning will depend upon the software that came with your scanner. The following will, hopefully,'point you in the right direction' but (without being able to see which program you're using) it will inevitably be a bit vague:
1. Put the newspaper article into the scanner, face down onto the glass. (There will probably be markings indicating which corner it should be aligned to).
2. Open your scanning application. Sometimes there's a standalone program for scanning but sometimes you have to open an image manipulation program and go to File>Import>(Scanner name) to start the scanning application.
3. There will probably be some menu options for 'colour photo', 'black and white', 'grayscale' (horrid American spelling!), etc. Select the appropriate one.
4. There will probably be a 'Preview' button. Click on it and you'll see a low-quality copy of the article appear.
5. Look for some dotted lines, either along the edges of the article or at the edges of the preview screen. They define the actual area to be scanned. If the lines haven't automatically aligned themselves to the edge of the article, click-and-drag them to the correct position.
6. Click 'Scan'. The article should now appear in your scanning or image manipulation program. (You might need to close the scanning window in order to see it).
7. Go to 'File>Save As' to save your scan to your chosen location. (Select the jpg file type).
8. Create a new email for your sister. Click on the button to add an attachment. Browse to the location of your scanned file and double-click on it. Send the email.
Chris