I need to file an IT-140 for the state of West Virginia, but I'm unsure of how to do so. Is someone able to assist me?

Did you select West Virginia as your resident state when completing the My Info section of the TurboTax online edition?  If so, then after you have completed the federal tax return you will be able to complete the WV state income tax return.  Just follow the interview questions in the state section of the program.

But...note that the WV forms are not scheduled to be ready in the software until after 4 January.