I struggled trying to use a mixer into my soundcard mic input and then using Audacity. I had so much noise in my recordings , I spent more time removing noise than anything. I struggled and tried several interfaces and returned several. I tried a Presonus Audiobox Usb interface and I was able to figure it out fairly easy and I have been happy with it. It only has two inputs but it works for me , for guitar and vocal. This little box sells for $ 149.00 with software and is a good buy.
I tried a unit packaged with Cubase and I just couldn't figure it out and got discouraged and returned it. I think an interface would help you out. Good luck , i know the feeling , kind of helpless with all the new gadjets out there