It will be to your advantage to engage a Realtor's service when you purchase your first home. Your Realtor will run a comparable market analysis for the specific house giving you an idea of how much similar houses sold for in the similar location during the last months. She should also be able to explain to you why those homes sold for that specific amount, and give you forecast on how the market is. This will allow you to make an informed decision rather than just looking at Zillow (which is not so accurate in a lot of situations).
Your Realtor will also be able to explain and guide you through the whole purchase process, include makeing an offer, negotiating on hbehaolve of you, conduct inspections, assist you to make sense of inspection reports, help you determine credit backs and guide you through closing.
You will not have to pay for your buyer's representation (the agent wll be paid at close of escrow only using part of the sales proceed fom the seller) This is your first home, help from a Realtor is very iimportant!