I HAVE EDITED THIS POST SIGNIFICANTLY AS SOME OF IT WAS WRONG !
Carole , here are a few more things I learned about working with MrSite which may be of use if you revamp
THE FIRST THINGS TO DO BEFORE MAKING ANY CHANGES TO PUBLISHED PAGES YOU ARE "HAPPY" WITH IS TO GO INTO "CREATIVE MODE". SELECT THE HTML VIEW, AND COPY THE CONTENTS.
PASTE THESE INTO NOTEPAD OR SMILAR (NOT WORD OR OTHER PACKAGES WHICH WILL APPLY FORMATTING.)
IF YOU MAKE A COD OF YOUR CHANGES SIMPLY PASTE YOUR SAVED CODE BACK IN WHEN YOU ARE IN HTML MODE AND NO DAMAGE DONE
OK that is a bit simplistic but you get the idea
For formatting pictures or text within tables if you right click in the cell you want to format and hover over the "Tags" option. These relate to HTML formatting commands. If you select "TD" it will allow you to define the format for that cell (e.g. image or text top align etc.) TR is to format rows there is also TBODY TABLE & IMG
The most important thing is don't make any mistakes! This may just apply to tables but if you format things correctly first time it's fine. As soon as you mess around with bold, underlines , bullets it gets it's knickers in a twist. You can fix it by correcting the HTML delete it and start again or use the "backup" method at the top of the post.
If you are bulleting anything apply your font and size formatting first and check it is correct before bulleting. If you change it after bulleting, it can be a pain and may need re-done.
If using bold in a table it can get confused and bold things you don't want bolded and you can't turn it off with the button. Edit the HTML (often every line needs edited ...) or delete and start again or "restore" as per above...
You can take a copy of you pages / images with FTP and store on your computer ...... but there is a snag if you plan to use them as a MrSite backup.
The html files you see in your wwwroot directory are not the ones MrSite uses as your "edit" source. What this means is you can take a copy of your pages. If you screw up your published pages with a MrSite edit you can copy them back from your computer and a browser loading the pages will see your restored pages. The snag is if you still want to use MrSite to edit them, it will load in the knackered version you previously published ..... and couldn't (or didn't wan to fix).
Just copy the html using cut and paste as described above if you want to use MrSite as the editing tool
If working on new pages to replace a working site , create them , name them close to what you want (eg HOME_NEW). mark them as Hidden with the admin function and develop them until you are happy. They won't appear on your menu but you can access them if you know the url. You will be able to access them from your browser using the page number (e.g. HOME_NEW is page Hidden page 13 so use
www.yoursite.co.uk/page13.htm )
When you are ready to go-live use the Admin function to shuffle into the correct order , hide your original pages and do your renames. Your old ones can be swapped back in if needs be. I thought it might not let me replace the Index page but it does.
MrSite is nearly very good. If they had a decent manual which told you about all the features available and had some guidance on how to use their tools to do something other than basic formatting I would have been much happier. The way the formatting gets confused is pain but you learn to work around it.
The lack of choice of menu sizes and location is a big restriction. They just need a bigger choice of designs (rather than lots of different colours / backgrounds using the same layout) .
It has served a purpose and I have no idea how it compares to any competition so I guess it has been OK , if somewhat frustrating at times
Good luck if you decide to revamp. I'm still working on mine ...
PS. SORRY FOR SHOUTING 
Did you pick all that up in a couple of days ? 
but I don't know what FTP is!