The forum can be a lot to take in particularly if you want to take it all in at once. My advice is to set a plan for what you want to learn and follow that, this will guide you on how to read older posts you search for.

For example, you can plan to learn about wallets, then nodes, then transaction details. You'll then proceed to search for posts with information on what you're looking for. You can use the same pattern in trading threads, only follow boards you have interest in to narrow down the amount of information you consume.