1stly DON'T use the mic in socket. Use the LINE in.
Use the aux out or record out from your amp so that the phono signal has been through the RIAA standard phono preamp so that the signal you record is at a recordable level & is corrected to compensate for the mastering process etc.
You also need to double click the vol icon on the bottom of your screen. When the mixer dialogue box comes up select options, properties, click recording, select & click your input devices, set some experimental levels & then the same for playback.
From there you SHOULD be alright BUT
Then you need a program to record into. There are lots of FREE ones like Audacity that can & will do the job.
IF, however, you want to restore the sound by removing pop, clicks, smears etc you'll need a program set up for that purpose.
I've been recording vinyl to burn to CD for about 6 years. I started off just using the wave recorder that came with the windows software. The computer soundcard was generic also.
I soon found that recording & burning as the LPs were left a lot to be desired.
I searched & researched for a few weeks & eventually bought WAVEREPAIR . It cost about US$30 but was the best decision I've made to date regarding old LPs.
Now I can manually or automatically clean up the scratches & pops. I can remove the noise of poorly made in the 1st instance recordings & do the same with tape noise.
The software will also find & separate tracks from the recorded file, normalise, EQ, - a whole bunch of stuff needed to have the plastic ready for burningonto CDR & it doesn't need a high powered machine. The author also updates the software frequently & FOR FREE.
I can't sing it's praises enough.
I actually have a better restored LP burnt to CDR than the CD reissue of it.
You will discover, also, that a stock standard soundcard will need to be upgraded to get the best results.
Oh & there's virtually NOTHING that comes anywhere close in the MAC market.
