Crankbaits are available in a huge variety of sizes and colours. But as a general rule crankbaits are stubby type lures, usually with two treble hooks attached and a lip. The size and angle of the lip determines the depth the lure will go to whilst being retrieved.
The faster the retrieve the deeper the lure will dive under the water. So it is worth doing a few long casts first off to cover some water and getting the lure to dive some distance.
A straight forward retrieve can be enough to get a crankbait working and catching fish. But if this doesn’t work, as with almost all lures try varying your retrieve with some short tugs and pauses. Always figure out what kind of depth your lure is working at, in relation to what depth the fish are at.
Salmo are one of my personal favourites.