By HTML and CSS you can design a good web site ...
i think these are essential an enough...
but for your logos and some buttons ,you have to know the photoshop...And need flash to show aour site little bit better...but it takes time to load...

You can use dreamweaver.

Dreamweaver can be very expensive and also confusing tool for beginner, please keep that in mind.

If you have time to spend in the website try doing it simply in text mode...
If not consider on taking a Dreamweaver course, its worth the money =]

The only reason you should consider Dreamweaver is because it's an industry standard. If you don't plan on making your life career in web, don't bother. Dreamweaver has many features in it that will write code for you, and I've never seen a site written in Dreamweaver that was semantically correct. For those of us who actually care about semantics, we'd rather hand-code all of it. You can use Dreamweaver, but at least turn off all of the auto-completion garbage.

On that note, I would either use PsPad or HTML-Kit. Both have built-in FTP support and are very customizable and light weight.

If that's too much, get an FTP program and bust out Notepad.

For website design use photoshop and flash and for for contents formatting use HTML and CSS and if you need data transactions then go with PHP and MySQL

Photoshop is something must have it for pros, however nice design can be done in other applications such as FireWorks or Gimp. HTML & CSS is something of must know it, without that what is point of web design. PHP and MySQL is something you have to agree upon after considering. As Java programmer I will say always JSP is more secure then PHP, but PHP has faster learning curve. MySQL is obvious choice but do not forget there are other databases. MySQL is good for small and medium size businesses. Want to support something large Oracle is better choice.
Lastly for the flashy effects I will rather go with Flex and other technologies grouped under RIA then Flash that is not so flexible.

Here is a list of free (actually free that is, no trials or anything) tools you may find useful:

Notepad++ - use this as your text editor - has syntax highlighting and line numbers (the two most useful features of any £1000 dev program)

Paint.net - You can do most web related image editing, using layers, and much faster than PS (obviously doesn't contain the same feature set, but the main ones are there)

Filezilla - open source FTP client - particularly easy to use and works well.

Those are the top 3 essential *free* apps for web development.

Also, remember the w3c site - combining the info there (and practice pages) with any text editor and ftp will result in an awesome site.

If you are concerned about the cost of dreamweaver there is a 30 day trial available from adobe.com - might be worth checking out.

Google for download links!