Many graduate students have not been trained to think of research in monetary terms. Some may experience difficulties when outlining and justifying a budget. Do not fear, however! Presenting a budget is not as intimidating as it may seem!
In the event that you are applying for an award that requires internal institutional coordination, there are numerous campus resources at your service, including the Director of Graduate Research and Awards in the University Graduate School, as well as the Office of Research Administration.
Many grant budgets are very circumscribed, with the funder explicitly mentioning the costs that it will and will not cover in the request for proposals. Funders also tend to be explicit about the format in which they want to see the budget, i.e., a form, a table/chart, and/or a budget narrative describing the rationale for funds you have requested.