Display help QAs from the database.
Insert new user questions to the database.
Update database.sql
Add filtering for ad viewing on ad listing page

Add filters. Save chosen filter in session & cookie.
Add new 'ad_priority' field into database.
Add CAPTCHA on ad inserting preview page.
Show corresponding images of ads on ads listing page.

Show default, when ad has no images.
Show the images of an ad on single ad viewing page.
Add a lightbox to view ad's images full-screen.
Show first-added img on every ad on ads listing page.
Add logically named ad images and corresponding database fields in 'ad'.