Yes - there is always a member of staff at the test centre to help. However, even if you have never used a computer before you will find the test very simple. The on-screen instructions are very clear.
A member of staff will show you which computer to sit at and how to start the test. Before the actual test starts, there is a comprehensive guide on to how to use the computer during the test.
If you have a problem with your computer during the test, signal to a member staff, and someone will come over to fix the problem.