DuneIII MUSH requires that you get hired for a particular character by a Faction Head before you enter the IC world. Each faction head may have a slightly different procedure for hiring new players, although they're usually pretty similar.
Keep in mind that the approval process does take time; this is necessary to make sure that the characters on the grid are believable and consistent with one another, and that everyone has a well-defined role. This process also requires that you, the applicant, put thought and time into creating an interesting and believable character that fits the position he or she will occupy in the House to which you're applying. The faction head and any other members of the houses that you catch online will of course be able to assist you with your questions and ideas.
The following information should help you from step one on, whether you are new to MUSHing or an oldbie.