How to merge pictures using adobe acrobat? I want to add 20 pictures onto one page (like a collage) using Adobe Acrobat.

What am I am going to do with this one page is print it so that it consists of all pictures (on a paper like the Polaroids) and hang it on the wall as a big one.

Someone did this before and I asked for the software and he told me it was done using Adobe Acrobat. But I've now opened it and don't know how to combine them all onto one page. If I did the using a collage app instead, it will certainly lose quality. 

So if someone understands and knows how to do this, please help. Or if there are any other ways to do the same on a Mac (Photoshop, something else) please explain how as I have no idea where to start.
Open Paint on windows, click "paste from" and choose a picture from your pictures or documents to load onto paint, where you can resize it,or crop it, (if you know how),
Do the same for each picture you want , it drops on top of your last picture and you just drag it alongside where you can resize to match other pictures or not..
Once you have left a picture and started another you cant go back and change the previous one...
When done close "paint" and it will ask to save,and name, it creates a new collage and all original pictures still remain as they were..