I have a few questions on muscle building issues for an ectomorphic body with (TSH hormone level at borderline).I'd really be obliged help in this regard.

Also,
Any good online tutorials based on gym training and muscle building for men, kindly provide in this thread.
Also some good links to nutrition would be appreciated.

We need some goals, Sir.

Without that, I can only recommend a few things. One, ignore almost every supplement you see. There are very, very few supplements that are useful if you already have a balanced diet, and most of them are only useful while you are taking the supplement. A few weeks after you stop, it's like you never did it at all.

Unless you have a lot of disposable income and you really like fish, you want protein powder. That's about it. Maybe creatine,if you want to bulk up a lot and do a lot of heavy lifting. Everything else you can get from vitamins and a healthy diet, or is borderline worthless.

Secondly, make sure to do a lot of back and leg exercises. They get neglected because they aren't as impressive as a six pack or biceps, but if you want to be strong in real life that's where it's at. Your lats for instance are very rarely used in real life, unless you're a climber or you chop wood.

Your back is also the most easily injured and hardest to recover part of your muscle system, so make sure it's strong.

Lastly, be patient. Most of the guys that get big in a year or so aren't real strong - they're big. That scene in Zoolander where he's in a coal mine isn't far from the truth. Puffy pecs and a six pack does not mean strong; it means you workout a lot, and yourbody is starving.

But if you take it day by day, you'll build stronger muscle, and be more likely to keep it when you get old.

thank you Zack for purposeful informative inputs.

Remember, no curling in the squat rack.

https://www.youtube.com/watch?v=qiEa3NRNKpk