To obtain commit access, you will need to demonstrate you are serious by submitting a few good patches first. Then, you will need to select a username to use when committing stuff, and finally, you will need to send me the username you have selected, an ssh key, and the email address where you prefer email to be sent (I will forward any email sent to you, but not store it).
Note that if you would prefer to keep your communications with me private, you can encrypt your email using my public key.
Once you are setup with an account, you will need to use your account to checkout a copy of BusyBox from Subversion:
svn list svn+ssh://username@svn.uclibc.org//svn/trunk/busybox
You can then enter the newly checked out BusyBox directory, make changes, check your changes, diff your changes, revert your changes, and and commit your changes usine commands such as:
svn diff svn status svn revert svn commit
For additional detail on how to use Subversion, please visit the the Subversion website. You might also want to read online or buy a copy of the Subversion Book...