I agree with Joe's last statement. Get the original website designer to put it right.

Someone mentioned FTP through Firefox. I do that using FireFTP which is a Firefox add on. It works very well.

You can also get add ons for Firefox which allow you to edit a page on the fly, providing you have the necessary permissions and password to access the site. Quite useful for "Quick and Dirty" fixes of the type Joe Offer described.

If you are going to get involved in maintaining your own website, you really need to learn about style sheets and other aspects of current best practice. It is not difficult once you get the idea and it certainly gives good control over the appearance of your web pages and allows you to make them very readable. I converted my own website to using style sheets and while it was a lot of work at the time, it has made maintaining the site easier in the long run, though it is really now due for a major overhaul which I am putting off just now as it will take a bit of time to do properly.