Not mechanically inclined but also not helplessly inclined

First post really ever but I have a 2014 dodge charger 3.6 with 250,000plus miles I believe I’m getting a transmission whine just had power steering pump replaced it’s only noticeable when accelerating or around first and second gear never had the trans oil changed should I chance it and change it myself or take it to a shop after watching a few videos it seems simple what’s the dos and don’ts