Hi Rynaw
Just open a blank page in Paint. Click "Paste from" then select a jpeg. Then do the same again with the second Jpeg and adjust the position relative to the first one by just clicking and dragging he image. You can adjust the size by the handles at the corners of the selected jpeg. When you are happy with the sizes and position just crop round the two images and save the whole as one jpeg.
Sounds complex when it is written but when you have done it once it's easy. You can of course put as many jpegs in as you wish!
Hope this helps.