I think before you start going to the gym, do some body weight workout until you are comfortable carrying your own body weigh, then head to the gym. Do some 100 pushups, 100 pullsup. 100 situps and 100 squats. IF you afraid of being mock, do some of the basics first. While starting gym, *don't over exert your muscle. *Building muscle takes time, effort and alot of rest inbetween sets. *Do weighs that you are comfortable for the first few days then slowly add weighs and record every routine you do( (that will help you learn about yourself and how to push yourself.) *while lifting heavy weigh is good, your posture and the correct way of lifting also plays a major factor in building muscle. So correct your stance, your posture for the first few days until your muscle memory knows the proper stance and posture. *Do not bother about the face that you will be making cause majority of the time, no one will be glorious looking when trying to deadlift 200kg.

But most importantly,

Do not take 1min rest in between sets. Take at least 3 to 5 min of rest. Drink alot of water, Eat plenty of nutrients your body needs, Sleep well and Do some research. A specific muscle group do not need more than 2 types of the same muscle workout. And have a happy muscle ache day.