This article explains how you can add products in bulk:
Step 1: Go to Settings > Imports > Import Products
Step 2: Click on download template
Step 3: Open the template and populate it as follows:
(*Please note that the data that is shown is for explanation purposes only and you will insert your product data)
Step 4: Save > Click on Browse and choose the file that you just populated > Click on File select
Step 5: You should now see a window like this ( see screenshot) if you are happy with everything you can click on "Import Products"
Step 6: You should see this window when complete
I have linked an article here, Import templates, which contain all the templates that can be used to do Imports with.