Best forms to learn grammatical english in few weeks

Hi! I came here with hope of learn (or find) people that help me to learn english for an exam that have in less of two months.

 

I have serious problems to build phrases in english, and in this exam I have that write a text of 80-100 words about a topic. ¿What methods you recommend me for this? Specially I need practice writting.

 

If someone offers to help me with this, I can teach spanish very well (I'm native :))

 

Thanks for your tips and any help.

Greetings!

 

PD.: I appreciate that correct me this text for learn about the mistakes that I committed.