Please give me advice on how NOT to pop my child? I'm going to lose my mind?

My daughter is 2. She is having meltdowns over everything. She will have a meltdown (fall to the floor, screaming/crying) over NOT being able to get her way. Example, She'll have a meltdown over not being able to climb on the table or get into the fridge. She'll have a meltdown over one of us parents going outside to make a phone call. PLEASE GIVE ME ADVICE. How do I handle the meltdowns?! I want to pop her to make her stop screaming, but I don't believe thats the right thing to do. I have a 7 month old also, and she starts crying when she hears her sister screaming.