Download the DC or DC++ software and install it on your computer.
Create a shared folder and a download folder on your hard drive and copy the files you want to share into the shared folder.
Ensure that the two folders are both shared by adding them in your DC settings
Ensure that you have at least two slots open
When entering the hub for the first time contact a hub operator to have your files checked to avoid being kicked for not respecting the rules.
For a DC and DC++ guide see the official hub website