Hi Haider,
When you create a file in Google Web Designer, make sure the environment is AdWords.
Author your content (check the Ad Validator panel to make sure all tests pass.
Publish > Publish locally as zip.
Select the Ad tab (you might need to create a campaign first).
For a non-dynamic ad, upload the zip file as an Image Ad.
For a dynamic ad, upload the zip file as an ad gallery
To upload multiple sizes at once, see this
post.
Hope it helps.
San
Google Web Designer team