Link Problems

I Have the ClassiPress theme installed. Its Not A blog Its for posting classifieds. I cant get my links to work right I have tried everything permalinks inc. There is nothing wrong with the theme. I really need some help on this cause I want to finish the site. The Name of my site is https://killaadvertising.com categories link dont work plus It dont show up in my pages in wordpress. Post an ad link/button has a 404 error. And when your logged in you cant view dash bored or edit your ads. Note: I have read for hours on other forums and tried many things. I will even get access to someone if they want to help me out. Thanks alot