The video above shows you how to add and subtract fractions with like denominators. Since adding and subtracting are so closely related, both topics are included in this excellent video.
The above video shows how to add and subtract fractions with different denominators.
When adding fractions where the bottom numbers (the denominators) are the same, you add the top numbers only (the numerators) to find the answer.
For example, 1/4 + 2/4 = 3/4.
Use these search terms to find your own resources:
adding fractions like denominator
subtracting fractions like denominator