After you have downloaded 7-Zip and installed it in your computer, you should come to a screen that looks like the one below.
Now, you want to go to the location where your resized pictures are located, which in most cases will be in the “My documents” folder.
Then you´ll see a screen like this. Remember that all pictures must have been resized to 1600 pixels using whatever software you would like.
In order to select all the pictures, you need to click on the top picture, hold “Shift”and then click on the bottom one.
Click on the “plus“ icon. You´ll see in this tab you can choose any of the following formats: 7z, Tar, Zip.
Zip is the most universal format so you might want to choose it.
Click Ok and wait as you see how pictures are being zipped.
You´ll notice that there will be a new folder in the list. This is the folder that you want to use to send your pictures. It will contain all the zipped files.