¿He escrito estas frases bien?

[jellybabe]

He escrito esas frases bien?

cuidado no se derrames, (mind you don't spill drink on yourself)

No quiero que se lo derrame ( I don't want her to spill it on herself)

estaba bebiendo agua en el coche y se le ha caido (she was drinking water in the car and spilt it all over herself)

[AngelicaDeAlquezar]

On top of writing boxes in the forums there is a drop-down menu to insert accents and other Spanish characters. Spelling is important.

Your first sentence needs more work. The other two are ok.
*** (Never forget to insert opening question and exclamation marks) He escrito esas frases bien?

Cuidado, no se (You need to use the right pronoun here for "tú" and add the direct object pronoun or the noun for the drink) derrames, (mind you don't spill drink on yourself)

No quiero que se lo derrame ( I don't want her to spill it on herself)

Estaba bebiendo agua en el coche y se le ha caido (Use the right spelling) (she was drinking water in the car and spilt it all over herself)