I thought these videos from StatQuest for learning how to do Stochastic Gradient Descent were pretty excellent. If you’ve forgotten how to do things like compute the sum of square errors and all that, it goes into good detail on how to compute that as well. The videos are all very approachable.
Video 1 - Fitting a line to data, aka least squares, aka linear regression
Video 2 - Gradient Descent, Step-by-Step
Video 3 - Stochastic Gradient Descent, Clearly Explained!!!