ok. this is how i do it. open paint (or photoshop, or whatever). it will automatically give you a small square of workspace. go to the corner until you get the arrow that will allow you to drag, thereby increasing the size of the workspace. save this as "collage". then open up another paint window, open pic #1, go to select all and then copy, and then go to the collage screen and paste it in. you can then move it around to wherever you want in the workspace. hit save. open pic2 in the other paint window, select all, copy, paste that into the collage too, move it where you want it and save. (make sure you save as a jpg file if you can.) then upload the collage into your post.
Perhaps I cheated, but I have my pictures uploaded to the internet already (on snapfish but there are others) so I could share them with family and on another site I visit, so I just used HTML tags to insert multiple pictures in my post.