Do you stressed out because で (de) and に (ni) are confusing? Actually, they are not that difficult as a place particle. Japanese Particles are so confusing! The hardest one is で (de) and に (ni) . Why? Because there are so many usages and meanings. Wait for a second. In English do you say "go at school"? Absolutely, Not. [Place Particle に] + [Movement Verb]
Movement Verb : いきます、きます、かえります etc.
[Place Particle に] + [Existence Verb]
[Place Particle で] + [Action Verb]