I'm an average guy. completed a 30 days challenge recently. The results are quite 'better'. I want to gain weight and mass muscle. I bought platinum Iso whey. My cousin highly discouragedd me to not use a whey protein. I told him I'll join gym after Ramadan In Sha Allah. But he forbade me. What should I do? I'm 7-8 kg under-weight.
With building muscle (especially if you are underweight), you want to be in a slight caloric surplus and consume between 1.5 and 2x your kg bodyweight in grams of protein. More is fine, not necessarily beneficial, but not bad unless you go crazy with it (like getting close to or over 300 grams).
So let's say you decide to do 150 grams of protein a day, you would then want to plan and break that up over multiple meals/snacks throughout the day. Why? Because you want to consume a reasonable amount of protein at a time, your body won't absorb 150 grams in one sitting the same way it would absorb 150 grams across 5 sittings. So try to do 3-6 meals a day getting 20-40 grams per meal as your protein goal dictates.
Should you use whey protein? That's up to you. It's not necessary, but it is a great option as a post-workout protein source because it is absorbed quickly. Your main goal should be to get enough protein in throughout the day, and going a step further, reaching that goal by consuming reasonable amounts per meal through the day. Ultimately, whey is just one of many sources of protein.