Open "Microsoft Paint" if you have Windows or "Paintbrush" if you're on a Mac. You can also download "Paint.NET" which is an open source program that will make it easier for you to create your photo collages.
Click "File" > "New" and enter the size you want your collage to be in pixels. In "Paint": Add a new photo to the collage by clicking "Edit" > "Paste From." Navigate the folders on your computer and select your photos. In "Paint.NET": Click on "Layers" > "Import New File" to do the same.
Click and drag the resize arrows on the corners of each new photo and size the photo so it fits the collage. Rotate the images in "Paint" by selecting "Image" > "Flip/Rotate." In "Paint.NET": Click "Layers" > "Rotate/Zoom."
Click and drag the photos with your mouse and arrange them into a formation, such as a round cluster, a heart or any free-form arrangement you like. Save your work and give it the file extension .png or .jpg so your can post it on the Internet.