I know we all have confidence tucked away in us somewhere; we may use it for our day life (i.e sports, odd job at home, etc). How can we develop confidence in trading?
For most, confidence comes with knowledge and experience. To understand more about how investing works, read articles about types of investments that you're interested in and browse the questions on this site. To gain experience, start with a "paper money" trading account. Most brokers will allow you to apply for a "fake" account so you can practice trading with simulated money. Once you've built up some confidence, you may wish to start investing a small amount of real money.
The right way to develop confidence is to get educated. Confidence can come from many sources, but the right source of confidence is an understanding of how markets work.
Markets react (and overreact) to news. I think the biggest factor to trading successfully is to not allow emotion to drive you. You should determine how much you are comfortable gaining and losing and set those in limit and stop orders rather than just using market orders all of the time.
As I've grown in my understanding of the market, I find it much more rare that I feel confident enough to make a specific bet. Most of my money is allocated in index funds, and I only buy and sell small amounts to reset the percentages according to a preset allocation plan. I still keep some cash available for speculative trades in the account where those trades will add the most value.
As other people have posted starting with "fictional money" is the best way to test a strategy, learn about the platform you are using, etc. That being said I would about how Fundamental Analysis works .
Fundamental Analysis is the very basis of learning about an assets true value is priced. However in my humble opinion, I personally just stick with Index funds. In layman's terms Index Funds are essentially computer programs that buy or sell the underlying assets based on the Index they are associated with in the portion of the underlying index. Therefore you will usually be doing as good or as bad as the market. I personally have the background, education, and skillsets to build very complex models to do fundamental analysis but even I invest primarily in index funds because a well made and well researched stock model could take 8 hours or more and Modern Portfolio Theory would suggest that most investors will inevitably have a regression to the mean and have gains equal to the market rate or return over time. Which is what an index fund already does but without the hours of work and transaction cost.