Marjorie ... Along with the above, I offer this ... I just purchased an Alesis Multi Mix 6 FX (it's stereo)for $99 that does a great job... plug the kb (I have a kn-6000) into the mixer and the mixer out to a stereo adapter into the PC sound card ... Depending on the recording software you may have to go into the PC 'Control Panel' and change the speaker controls to 'record' ...
Using the mixer gives great flexibility for eq, especially if you are also doing vocals ... If so, I also recommend laying down the kb track first, then a vocal track ....
good luck, and have fun ...
t.