I am asked this question alot. So I would love to say... it's easy!
But that would be a lie.
It can be easy, it depends on the images you are working with, the backgrounds they are originally sitting on, and the resolution they are in.
There are lots of great online resources on using Photoshop to cut out your backgrounds. Then you can layer them all together on a white background. And finally, you can add text and numbers.
Or you can come to the Intermediate Photoshop Workshop that I'm doing in Sydney and we can eat nice food and work through all this stuff together at Megan Morton's school. Making digital collages can be fun!
And here is one I prepared earlier. I just can't get enough of that yellow teapot.
1. Porcelain jugs www.kaufmann-mercantile.com
2. Leather tote www.shop.uncovet.com
3. Enamel teapot www.kaufmann-mercantile.com
4. Rope necklace www.spreeglanz.com
5. Wooden brush www.kaufmann-mercantile.com
6. Geo pillow www.gormanshop.com.au
7. Potted succulents www.ikea.com