When you exported your page design to Dreamweaver did you have it sliced up into a table? If so, did you contain your welcome text within one cell?
If this is the case then go into Dreamweaver and select the cell that currently has your welcome text in it. As you know, you currently have your text as an image file, which isn't necessary (plus it means your page takes longer to load).
If you delete the image which is your welcome text you can then just enter regular text into the cell instead.
The next time you create a page in Fireworks, bear in mind which elements you want to keep as graphics and which will need to become text and slice up the page so they're kept separate of eachother. If you make sure they all go into their own cells then you can adjust them as you need to in Dreamweaver.
Another thing you may come across - Fireworks will make graphics for individual cells that contain just a single colour. Again, these cause your page to load slower and they're unnecessary, so delete them in Dreamweaver and just change the background colour of the cell to the colour of the original graphic (remembering to add in a non-breaking space to the code to keep the cell from collapsing in Netscape).
I hope I've been able to explain what's happened, but if not then maybe someone else can explain a bit clearer or I can clarify things you're unsure of.
Julianne