In simple words:
technical analysis look at the past price trends and looks for the patterns between these trends and data (price, volume and etc). In most cases data are represented by indicators that are based on these data. When you finds the patterns, technical analysis assumes that in the future we may see these pattern repeated and this knowledge helps to predict future trend development. As an example, if in the past in most cases we see price declines when RSI drops below 70% after being above it, then when we see it next time the odds are good we will see a continuation of a decline.

First step, I would say, is that you need to decide what you gong to trade - forex, futures, stocks, ETFs and etc. Depending on the choice you may need different analysis to perform.

Then you need to find out what time frame you want to trade. Again it make difference what analysis to use. If you decide trade stocks in long term you may need add fundamental analysis to your technical analysis. On the other hand, if you plan to make several trade a day, fundamentals will not help you a lot.