To enlarge, do this: first right click on the image concerned and choose 'save picture as' - this means you are effectively savng the picture to your computer, so choose a location on your computer where you will be able to find it again!
Then navigate to the folder you have saved the picture in, using 'my computer' or windows explorer.. You need to be looking at the list of items, or the list of thumbnails, which includes your picture.
Right-click on the picture in this list and choose 'open with' from the list of options. Then choose >> 'microsoft office picture manager' from the next list of options. This will open the picture in this program. At the top of the browser you will see a box with a % sign in - this is simply showing you the real size of your picture. Look to the right of this and you will see a button marked 'edit' - click this.
Then from the list of options on the right of the screen choose 'resize'. You will have to fiddle a bit as the pre-set sizes then displayed are all aimed at reducing rather than increasing size. Save your work when finished.