There are several ways for you to contribute your own datasets to Aleph. The method you choose is dependent on the type of data you are attempting to add:
If you want to upload a small number of documents, create a case file using the user interface and upload your documents using the upload function inside that case. You can share a case file with some colleagues who have accounts on the site, but it cannot be made public.
When faced with a large trove of documents, such as a leak, use the command-line based alephclient tool to submit documents in an automated fashion from your own computer.
If you plan to regularly import data from a public source, such as a government web site, you may want to create a web crawler that automatically executes, collects data and submits them to Aleph.