You would need some sort of capture card/unit.
Be aware this may be the cheapest but not necessarily the best way.
I have a Dazzle Fusion USB capture unit but it takes about 7 hours to do a complete VHS/Beta 3 hour tape.
I have now got a DVD recorder which transfers in real time. eg. a 3 hour tape transfers in 3 hours. Can't offer you a link to Dazzle Fusion as it does not appear to be available any more.
But DVD recorders from here: click here
I have the Liteon 5006 (second one down)