anoying sound when recording

[mullet0909]

so i downloaded some freeware (krystal) to record with. I plugged my bass into my bass head and used the "line out" going into the "line in" on the computer. the speakers give off an anoying hissing sound when im plugged in. I cant put the amp volume too high or its distored but the turning up the volume on the program amplifies that terrible hissing noise and it goes onto the recording. goes onto the recording. any ideas on how do fix this? what im doing wrong, and if i need to change anything or get something different.