In reply to Rog Wilko:
Its similar to the london underground. There are ticket machines at every station that print physical tickets. The stations are grouped into zones [1]. City centre is zone 1 and Salford Quays is zone 2. Just buy a ticket covering zone 1+2, single or return as appropriate, and keep it on you while you travel. Like the underground there are maps inside the carriages. Depending on your starting station you might need to change at Cornbrook. See the map at the link
There's also an Oyster-like tap in/out system but as a visitor its probably easier to just buy a ticket.
[1] https://tfgm.com/tickets-and-passes/fare-zones/tram
Post edited at 00:28