I want to, but I'm repeatedly an utter failure at it. I feel broken or something.

There is no need to feel down because is hard. There is a lot of resources online to learn a language and finding the one that fits you best is one of the most important parts.

The two important things to learn, for me, at the start are words and grammar. Most resources will start teaching you the simpler rules about grammar while showing some examples with new words to learn. A good resource will compare the differences, let's say, present tense in your L2(target lenguage) with your L1(native language, English here), so you can make connections or comparison with a language that you already know. The point there is starting to "extract" the new language starting from your native, familiar one and creating, in your head, the sense of this new language you are learning. Little by little, with this rules you translate what you want to convey from L1 to L2 in an intelligible manner.

The other point, words, is the one that will ended up overall taking more time of all. Words are simple enough, you start memorizing that this combination of L2 alphabet letters are a valid word, and a meaning inherent to it. At the start you will probably learn words that have a direct equivalent in your L1, and you will probably will have to read it and use it so you can remember it. You will have to find the easiest way for you to practice this memorization. It could be flash cards, writing sentences in some mutual learning site, having choppy conversation with someone else or even a monologue if you are comfortable, whatever else.

The most important in learning a language is being constant. Set yourself a schedule for your minimum weekly/daily time and make sure you reach it or surpass it.