Lots depends on what kind of programs you're familiar with. You could do this in any of the usual Microsoft Office (other versions of office software are available) but some will be simpler than others.
eg Word - likely to drive you crazy as the images will tend to jump around as you work
Publisher - will do the layout fine but can be daunting at frist if you've not used it
PowerPoint - an oddity to suggest, I know, but I find that it's easier to get to grips with than Publisher
The key will be to ensure youre 'paper size' is big enough for your project. In all of the above programs you can choose an A3 format.
Have a look at these programs if you've got them and also riffle through help videos on Youtube for adding images, text etc if you get stuck.