Hey Simona.
Just making sure I got this. So you dont have enough light, the location has no windows and you need to add more light to your scene but you only have 1 practical motivated light.
Well if you have no windows the only option is to add a few more practicals, (maybe a standing lamp, candle light) with these practicals in place you can a add a few soft lights( kinos) into the scene to get the right amount of light., all depends on what look you are trying to achieve.