Look at Gardeners World on the BBC website, every Friday. They have had 3 programs in their new series and I think it was the 1st, in early March, that covered raspberries quite well. You can look at previous programs online.
Raspberries grow very easily. Simply look around the base of an established bush and you will see shoots of new bushes appearing. Dig them up with as much of the root as possible. Plant them in your garden, water well.
When you take a shoot, make sure the surrounding raspberry plants look healthy.