Zotero offers a free and two-paid for versions. For most users the free version provides adequate storage and functionality.
To register go to Zotero.
Zotero has a web and a desktop interface; to access all the functions of Zotero you will need to use both.
Imperial PCs in the Library and PC clusters have Zotero desktop installed.
To download Zotero desktop onto your own machine click on the Download button and follow the installation instructions.