"I would like you to paint both ends of the this rectangular board red."
"I would like you to paint both ends of the this rectangular board red."
"I would like you to ~" 「〜てほしいんだ」"I want you to ~" や "I need you to ~" も友人にはつかえますが "I would like you to" は一番丁寧な言い方です。
"to paint" 「塗る」
"both ends of ~" 「〜の両端」
"this rectangular board" 「この長方形の板」
"red" 「赤」