Hey
Your site seems a bit too spaced - that is there is lots of unused space. The blue bar at the top does not do anything. There are some gifs which are animated. Be careful with those because they can get annoying when reading the page.
There is no welcome paragraph nor is there much META. You can add far more to your meta description check out
www.wordsinarow.com for good search engine optimisation techniques.
Why is the page "http://www.smoothstoneservices.com/webdesign.html" and your index in html when your other pages are in ".php"? You can use includes if you are using php which is helpful when you are making global changes. I think there is a search benefit for having an index page in .html but I'm not sure.
For the page Computer Tech Support you have got the text "~ Quality Services That You Can Count On ~" why is this? Also in the title of the page you have got "||" and "::" and some with none, which is inconsistent.
I would try texturing your navigation and getting rid of space which isn't use. Change the font to something like verdana
You are very much not using valid HTML as stated. I would take off that link until your code is valid. You have 1 error in your stylesheet
http://jigsaw.w3.org/css-validator/validator?uri=http://www.smoothstoneservices.com/&usermedium=all
There is no link for "Browse Available Templates!" on the main page. The page "http://www.smoothstoneservices.com/webdesign.html" has no link to the pages "Recycling Service" and "About The Founder" and the text "Our Services" is not there on the index page.
Keep at it. Have a look at some tutorials like
www.htmlgoodies.com and
www.alistapart.com.
www.w3schools.com is good too for reference.
If you are looking for certain effects and techniques on how to design something, try searching for it on google.