Choose two level 3 spells in your spellbook as your signature spells. You always have these spells prepared, and you can cast each of them once at level 3 without expending a spell slot. When you do so, you can’t cast them in this way again until you finish a Short or Long Rest. To cast either spell at a higher level, you must expend a spell slot.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.