You just think <about> how you are going to get that money together. You just worry about how you are going to get that money together. The first sentence should benefit from having the word about but is passable. However the sentences convey different ideas. Think about - means you are considering. Worry about means that there are problems that concern you. So the sentences are not equivalent in meaning.

Think about Worry about. And in this case if you say "that money" it seems like you´re refering to a particular momey, If you are not, then forget aboot "that" :) Los 2 verbos worry y thing siempre van acompañados de about, y cuando usas el that te estas refiriendo a un dinero en particualr, si es solo dinero en general no uses that. Un ejemplo si yo digo Yo amo la musica. En ingles seria I love musica. (porque hablo de la musica en general, no puedo usar I love the music ok. Espero lo hayas comprendido si queres puedes encontrarme en www.facebook.com/ytaro