If you didnt have very clear what end goes inside the scope and what end is to look through,I would not mess much with the eyepiece,!,,for now!
fit the eyepiece to the scope ,now that you know how and watch birds..
the celestron Regal Zoom is a nice eyepiece by the way,..A zoom eyepiece is very useful tool,and fun,specially for beginners,allowing you to learn the use and limitations of your scope...That 17mm eyepiece falls in the middle of your zoom range,and its a very useful magnification,probably the most used ..but you will find that lower and higher powers are a must ..
the REgal zoom has a pleasant Field of view at all magnifications..perhaps a tad wider angle than standard
8-24 zoom,and it is sharp with good contrast..My advice is to use that Zoom for now,learn to aim the scope and properly focus ..
maybe get some information and learn how to know if your scope is a good sample ,making some tests at high power..