You may want to review multiplying, dividing, adding and subtracting fractions first.
To evaluate an expression, you just need to do all the operations written. Be careful not to make any mistakes! Also, be sure to do them in the right order. Anything in parentheses should be done first. Otherwise, always do multiplication and division first, from left to right. Then do addition and subtraction, also from left to right.
An easy expression is 1. Your answer is just 1. (That was easy, because there were no operations to do.) A harder expression is −1 − 2 + 6. Since there are only additions and subtractions, we do them from left to right. So we do −1 − 2 and get −3. Then we do −3 + 6 and get 3, which is our answer. A much harder expression is 0 / (−2) / (3(−2)) + 1 / (−1 / 1) − (−1) / 2 * 2. First we do the parts in parentheses. We get 0 / (−2) / (−6) + 1 / (−1) − (−1) / 2 * 2. Now we do the multiplications and divisions. First, 0 / (−2) / (−6) is 0 / (−6) (remember, we go left to right), which is 0. Next, 1 / (−1) is −1. Finally, (−1) / 2 * 2 is (−1 ⁄ 2) * 2, which is −1. So we now have 0 + (−1) − (−1). Going from left to right, this is −1 − (−1), which is 0, so that's our answer.
If there are nested parentheses (one set inside another), deal with the inner set first. Often, the outermost set will be written as brackets [like this] instead of parentheses; this is just to make it easier to read. Also, someone may have taught you to always do multiplications before divisions, or additions before subtractions (as in the mnemonic “Please Excuse My Dear Aunt Sally”). This is wrong!