help with .htaccess

[impact]

This was originally posted at [webmasterworld.com...]

Hello,
I am trying to do this with .htaccess. Please help me to correct my code.

Things to do 1:
www.domain.com it should redirect to www.yahoo.com

Things to do 2:
www.domin.com/3454 it should take it at the server level as www.domain.com/index.php?url=3454

I am very new to .htaccess. Any help will be appreciated.
Thank you

[g1smd]

What code have you tried so far?

There's a similar question posed here at least several times per month, so there's a lot of prior example threads to get you started.