Hi,
You will need either a conventional hi fi type record player with amplifier and plug this into the sound input on your computer. You will probably need a phono to 3.5mm jack but check the back of your PC first.
Alternatively use a USB record deck such as this one from Maplins but other places sell them too, just shop around
http://www.maplin.co.uk/Search.aspx?criteria=N 62CK&DOY=26m7
Next you will need some recording software, the above comes with Audacity, which is free and can be downloaded here.
http://audacity.sourceforge.net/
Or you could splash out on this type of deck which negates the need for a PC, bit pricey though at �200.
http://www.maplin.co.uk/module.aspx?ModuleNo=2 24772&doy=26m7
Now you will need to set it all up, making sure the audio levels are correct and the sound isn't distorted. If doing LPs you will need to record each track separately rather than the whole album in one go. This way once the tracks are on your computer, each one can be named individually. Audacity can save in a number of formats including Wav which is uncompressed and Mp3 which is compressed. Using compression means you will get more tracks onto a CD at the expense of some audio quality, but with 78's as a source I'd doubt if you will be able to hear any difference.