I shoot a couple of Images and try to merge them with Lightroom. Since a few (but not all) of the shoots were taken with an ND-Filter. I need to somehow tweak the EV value of the Photos I took with the ND-Filter. Where can I set a manual Exposure Value in Lightroom?
I do not think you can directly change the exposure.
You can try to align the exposure on all the photos in LR using function 'Match total exposure". In Develop module select all the images in question, Settings -> Match total exposure. Or Ctrl+Alt+Shift M (on Windows)