[TYPO3-RTE] Default Textsize and Paragraph

[Karl Meier]

Hi
How can i set the default Textsize from 8 (seems to be the default) to 10 ?.

Although I changed the space between
the paragraph in the stylesheet of the Website to zero, rhtmlarea still 
shows a distance how do i change that ?

As I'm quite inexperienced in Typo3 and the creation of advanced Websites 
please answer in a sufficiently foolproof way :)
Greetings Karl Meier