Just use paint.
Open paint.
goto file/open
choose first pic and resize it using image/stretch-skew to keep image proportions.
now resize your canvas if needed using the small dots at the sides and corners to make room for second pic.
then goto edit/paste from
choose your second pic.
again resize it using stretch/skew. (the second picture may take a few attempts since paint doesnt let you hold a key (like photoshop) to maintain image proportions. Just use small amounts to get it the size you want it.
Position the second pic where you want it and then resize your canvas to hug the edges of the two pics to get rid of the white.
Then file/save as and save it where and in what format you wish.
Hope this helps.