Pausing execution without the form freezing?

See more:

C#

Here is some code in one of my methods:

webBrowser1.Focus();
System.Windows.Forms.SendKeys.Send("{PGDN}");

I'm using this to force the webbrowser to scroll down so that a picture on the site I'm using is on screen.

Then I use:

findClick();

I have coded this to mean: using(image1) find image on screen and click.
It works fine.

MY PROBLEM IS:
(here is the next line of code):

webBrowser1.Focus();
System.Windows.Forms.SendKeys.Send("{PGDN}");
Point one = this.Location; //at this section my program doesn't wait for the above two commands to run before starting this line
//it runs the code before the screen has been scrolled so my picture finder never gets found.

How do I wait for a certain amount of time before executing the next line of command?
THREAD.SLEEP DOESN'T WORK!!!!!!!!!!
This command freezes the form and doesn't do anything for this problem. I also cannot use timers because I need the code to remain in this method (preferably in one line, like thread.Sleep)

How would I go about doing this?

ANOTHER SIMILAR PROBLEM:

using:
webBrowser1.Navigate("http://google.com");
second command;
third command;

This doesn't wait for the first command to finish so I would like to place a timer that says wait(5000) then continue.
I KNOW ABOUT DOCUMENTCOMPLETED events, I'm using this as an example!