I am knew to character building, and as I am creating a sorcerer, I am a little confused about the spell vs. attack aspect. I understand there is a separate page for spells, but I am wondering how I should fill my attacks and spellcasting box on my character sheet. Should it be a combination of both spells and attacks? My character has a light crossbow and longsword in equipment. I'm also not really sure how many attacks to put. Also, how do I know which spells to choose from for the attacks and spellcasting section?
There’s no One True Way(TM) to fill it out.
That place on the character sheet isn’t so much of a hard stat (like your spell list) as much as it is a quick reference to your available means of offense.
It can contain weapon attacks, spell attacks, even things like Dragonborn breath weapons or even abilities like rogue Sneak Attack or paladin Smite.
It can contain all of them if you want them all up front, or just your most common ones, or it could even be blank if you’re comfortable with looking them up (promptly enough that your table isn’t left waiting). Whichever way works for you is ok.