Go to photos
At the bottom press the cloud in the middle - note you must be signed in to iCloud
Click on + New Shared Stream..
Type in the name you want to name the Photo Stream
Add the names of the people you would like to add to the Photo Stream
Add the names of the people you would like to add to the Photo Stream - they must have an iPhone or iPad and have signed in to iCloud
Select + to add items
You can select photos one by one by selecting albums at the foot of the device or in photos (foot of screen) press select to select all screenshots or photos in that collection of images
Like this.. That will select only all the photos in that collection (usually all the photos or screenshots taken on that day) press done
You can invite more people to view your Shared Photo Stream by selecting people at the foot of your screen
Let's add the two again
Easy as that practice sharing with a friend so you know you got it right.. Another arrow for your bow..