I will answer 3 questions with 1 different way for each.
Way 1. A number line.
1. (-6) + (+8)
Way 2. You can use words/money to help you.
2. (-8) + (+7)
Way 3. You can use circles. There are 2 different circles, a shaded one, and a non-shaded one. The shaded ones are positive, and the non-shaded ones are negative.
3. (-7) + (+9)
Hope these tips taught you how to add positive and negative integers.
Here is a video that may help you with