i'm not japanese but i'll help with what i know. when you add "tai" to a godan verb, you change the last letter from "u" sound to " i" sound. examples: 手伝う~手伝いたい 書く~書きたい 飲む~飲みたい but if the verb is ichidan, you just replace "ru" with "tai" without any changes to the verb. examples: 食べる~食べたい 助ける~助けたい

@Ryokoさん、いつもありがとうございます＾＾　@WCalCasさん、どういたしまして！

My pleasure!

Thank you Flora san and Ryoko san for clarifying as well! ^^

Ame-san's answer is correct. "I want to help" = 手伝いたい(です) or たすけたい(です), basically we translate like these but it's possible seeing Flora-san's translation on the subtitles or something.