Wayne Said:

What topic could i write about in my discursive writing essay ?

We Answered:

Here are a few:

Abortion

Prop 8

School Uniforms

Universal Health Care

Try to find something you are passionate about, but is highly controversial.

Clifton Said:

How long should it take me to write a 800 word essay?

We Answered:

When I was a high school sophomore my English teacher would assign 500 word essays to be completed during the 55 minutes of her class. The first I ever knew of these assignments was when I walked into the classroom. At least sometimes we chose thesis statements ourselves, but on the assigned topic, for which we would be have been prepared by our homework. For example, one essay was on the man Julius Caesar while we were studying Shakespeare's play and had completed some background reading assignments. 500 words in 55 minutes suggests that you should be able to write 800 words in two hours.
You're having trouble writing, so maybe you should sit down with the goal of 400 words in one hour. Come back after a couple of hours and write 400 words more. Then combine your work. Tomorrow revise everything.
Excellent writing almost always requires rewriting, so don't freak out if your first drafts are kinda poor. Get some ideas written out. Compile your thoughts. Revise the essay.