i like him　と友人が言っていたのですが、大好きならalotをつけた方がいいと思うのですが、alotを最後につけたほうがいいんじゃない？ってどう伝えたらいいでしょうか？you need to put "alot" end of the himとかになるのでしょうか？

教えてくださいい

If you really LIKE him, you might want to tell him so. Like"I like him a lot","I really like him."or "I like him very much."

or
You might want to add "a lot" or "very much" or something after you say "I like him" to let him know your feelings better. 　

If you wanna emphasize how you like him, why don’t you put "a lot" in the end? It’s like I like him a lot.