Yes, an interaction effect is formed by multiplying the two variables in question. In a regression, you would include the two primary variables as well as their product. If both the variables in the interaction are continuous, then you should look up "linear by linear" interaction effects to get a good understanding of how to interpret such a model.

Hi, David,

Thank you so much for your response. Then, my concern is that I will get the same score with different scores for each variable.

For example, even if I get 8 for the interaction effect, there are several ways to get 9 (2 and 4, 1 and 8, etc...), and this difference is ignored when I multiply these two variables. Isnt it an issue?

I suggest you try running the regression I suggested (two primary variables plus the multiplicative interaction effect) and see what happens.