Weight Gain Journey

Hi all,
I’m really new to the fitness lifestyle. My weight has mostly been consistent since high school (I’m 26 now) but since giving birth in 2017 my physical appearance has been unsatisfying for me I would definitely like to add more weight in muscle and booty gains and slim down in the waist area. I just started a routine workout regimen but would greatly appreciate any tips on nutrition and if you have any exercise suggestions for gains I would greatly appreciate it! Also looking for gym partners if you’re in the Chicago area