Finding the y-intercept when you have two points is pretty straightforward! You need to first find the equation of the line using the two points. For points ((x_1, y_1)) and ((x_2, y_2)), calculate the slope (m = \frac{y_2 - y_1}{x_2 - x_1}). Then, use the slope-intercept form (y = mx + b) and one of the points to solve for (b), the y-intercept.
What are the coordinates of the points you're working with? I can help walk you through the steps!