∑ is sum. Underneath the symbol should be n= a number (It could be any letter, but n is used most often.), and another number (or infinity) should be abover the symbol. The n=some number is the starting point, and the top number is the ending point of the sum. To the right of it should be a function that includes n. So, replace n with the starting point, and evaluate the function. Then, replace n with the next number, evaluate the function, and add it to your previous result. Keep doing this until you have gone all the way through the last number.
For example, ∑4n where n goes from 3 to 6 is (4)(3)+(4)(4)+(4)(5)+(4)(6)=12+16+20+24=72.
I watched the first part of both of these videos, and they look like they provide a good explanation of sigma notation (the ∑ symbol is the Greek letter sigma). The sound quality is poor in the videos, but if you can get past that, they should help you understand how to do summations.
Your other symbol, ∫ is the integral. To be able to do integration, you really need to study calculus. Once again, I only looked at the first couple minutes of it, but this video looks like it will give you a decent explanation of the integral. It is enough to give you an idea of what is going on, but without studying the calculus that precedes integration, you really won’t be able to get a firm grasp of it.