Eligible people are called “participants” and a planning assessment is undertaken by the National Disability Insurance Agency NDIA to identify the participant’s goals, aspirations, strengths, capacity, circumstances and context. The NDIA will use this assessment to determine how much funding they will provide. See here for more information.
You can self-manage, have the NDIS hold the funds and have your providers claim payment from them, or employ an NDIS-approved plan manager. See here for more details about your options.