yea solid meal is a must but weight gainer does help. sometimes its hard to eat up to 6 times a day. a gainer got more calories compare to whey protein and it got carb too which really good if u looking to gain.
multivitamin also a good way to start. it will help fill the nutrition and vitamin ur body needs

when i was gaining i got both whey and weight gainer. and of coz eating more frequently. whey are great when u wake up and post workout but weight gainer will gave u those extra calories u need. so my advise will be try it urself bro..