You have to write special commands into pointed brackets <>, and to end your command with a slash. These commands in pointed brackets are called tags.
b - /b in brackets: all in between is printed bold
i - /i in brackets: all in between is printed in italics
font size=+1 - /font in brackets: all in between is printed bigger.
e.g. < b > bold < / b > [I have to write it with spaces to show how the tag works, omit the spaces]:
bold
italics
font size=+1
After the end tag /font in brackets you revert to the original size.
font size=+2
font size=-1
Have a look at the FAQ section for basic Mudcat HTML.

Wilfried