A few folks have noted that they don't have much striking experience, particularly with basic boxing punches. I honestly don't have a ton, but have gained a lot by focusing with the bag or a training partner. For folks with limited access to training and/or strike training, there are some bad habits you can pick up trying to learn on your own from a book of manual. I've grown to really like Expert Boxing's Youtube channel. The videos are usually brief (<5 minutes) and emphasize not only basics, but nuanced details like foot placement, elbow placement, shoulders, and rotation in general.
If you're trying to learn, repetition is everything.
And always start with the JAB.
Here's some Expert Boxing Videos on jabs I've found useful: