Head to https://fbs.research.utexas.edu and log in.
Then select the calendar you wish to book time on.
Next click on the calendar date you want to schedule
Then double click on the time you wish to book
On the pop-up window select what type of time you are booking. Usually this is 'research' but there are options for discounted pilot time and free development time.
and then fill out an account number we can bill to or select your labs pay alias if you have set one up previously.
Then just schedule your start and end time and hit "save changes"