Training weights will have an effect on your weigh ins as your body compostion adjusts. Everyone re-acts differently. When I increase my weigh training my weight initially goes up, but comes back down again fairly quickly.
A word of warning about weight training. You will get bulky if you over eat or are over weight whilst building muscle. A lot of girls new to the sport think they can eat what they want and gulp down protein shakes. Body fat levels are very important in body sculpting with weights. Good luck!