Control variable?!

[iboha]

Hi,everyone, I am a bit confused on how to use control variable.
For example, if I am studying on the relationship between economic growth and energy consumption, and I would like to use capital stock(K) and labor(L) as the control variables. So in VAR setting(e.g. Eviews), I tend to put K and L in the exogenous variables box.However, can any expert explain what is the rationale behind it please?
In fact, I tried to put K and L in the exogenous variables box. Then I proceed but I found that there is no lag terms for these two control variables. Help please!Thank you in advance!