To manually upload your leads:
Go to the Users tab in the left sidebar.
Click the Upload Leads button on the top right.
In the upload window:
Click to upload and select a file from your device, or
Drag and drop your file directly into the upload box.
Once uploaded, click Upload to process your file.
After processing, your new audience list will appear under the Leads List table.
Your uploaded audience is now ready to be used in campaigns.