To report an interaction, you need to summarize the coefficients, standard errors, and significance levels of the main effects and the interaction term in your regression model. You also need to interpret the meaning of the interaction in terms of the research question. For example, you might say something like:
"The results of the multiple regression showed a significant main effect of teaching method on math scores (b = 5.23, SE = 1.34, p < 0.01), indicating that students who received the new method scored higher than those who received the traditional method. There was also a significant main effect of anxiety on math scores (b = -2.56, SE = 0.78, p < 0.01), indicating that higher anxiety was associated with lower scores. However, these effects were qualified by a significant interaction between teaching method and anxiety (b = -1.87, SE = 0.65, p < 0.01). This means that the effect of teaching method on math scores depended on the level of anxiety. Specifically, the new method was more effective for students with low anxiety than for students with high anxiety, whereas the traditional method was equally effective for both groups."