Hello,
First, make a new image (or a new document) big enough in order to contain others.
For example :
If you have 5 pics 1024 x 768 , so you should create a new document 1024 x 3840
Then open the folder that contains your pics.
and drag'drop them to photoshop.
At this point, you should have a lot of layers. Each layer should be one image you dropped.
Then resize and move each image (layer) in order to arrange them in the big image (the first you created)
When finished, save it at .JPG
