Am I likely to gain weight by incorporating exercises for my back into my weight training routine?

A little while ago I was informed that it's not good to just work your chest and not your back (which is what I used to do unless I went to an actual gym and did lat pull down). As a matter of fact, as I reflect, my back was probably the only muscle group I was neglecting which could explain why I haven't gotten the increased body weight results I've been hoping for. Last night, I decided to incorporate pullovers into my workout routine and today I feel that my lats are a little bit sore but not as it would on a lat pull-down machine but I mostly feel it in my triceps and posterior deltoids. I was wondering, if I continue along with this new exercise (and others for the back), could I expect some good weight gains? Thank you.