Many times, instead of requiring you to make a spell Attack roll, the Spells you cast will require those within the area or targeted by the spell to attempt a saving throw against your Spell DC to determine how the spell affects them. Calculate it using the following formula.
Spell DC = 10 + spellcasting Attribute Modifier + Proficiency bonus + other Bonuses + Penalties
When creating your character and adventuring you’ll record the total modifier for various important Checks on your character sheet. Since many Bonuses and Penalties are due to the immediate circumstances, Spells, and other temporary Magical Effects, you typically won’t apply them to your notations.
For example, the number you write down for your Attack modifier with your Battle Axe would likely be your Strength modifier + your Proficiency bonus with martial Weapons. Your spell Attack modifier is typically just your spellcasting Attribute Modifier + your Proficiency bonus, and your Spell DC is usually the same number + 10.
Item Bonuses and Penalties are often more persistent, so you will often want to record them ahead of time. For instance, if you upgraded your Battle Axe with a +1 weapon potency rune, you’ll want to add the +1 item bonus into your Attack modifier with the Battle Axe, since you will include that bonus every time you Attack with that weapon.
