Meta tags aren't gonna help. If you wanna rank anywhere near the top 10 results on Google (eg.: on this page: "sell house online") you will need to...
a) completely re-code your website
b) re-arrange your content, keywords and descriptions

I would try to give more productive feedback but I don't know where to begin. There are too many problems:
- code doesn't validate
- bloated pages (tables upon tables, inline css, etc)
- non-semantic code (h1, h2, h3)
- little content (some of which is replaced by images, which SEs can't read)

An easy thing to get solved right now, is to fix-up your URLs. They are very poor and have no keywords. This...
http://www.sellyourhouse4nowt.com/in...listingID=1730
...would be better as...
http://www.sellyourhouse4nowt.com/go...tion-portugal/
...and can be easily achieved with URL Rewrite.

Note: Re-design and re-code are separate things. You could have the website look exactly as it does now, SEO is about changing the information and how it's served, not what it looks like. It's about your content and how it's coded.