If you have a job, your employer may offer a 401k or 403b retirement plan as part of your benefits package. These accounts invest your money for retirement, but your investment options are limited to the choices provided by your employer and plan provider. If your employer doesn't offer a retirement plan, you can open an IRA on your own with your bank or brokerage company.

Say, a U.S.-based software company is trading at a price of $100 and has a market capitalization of $5 billion. A news item comes in that the EU regulator has imposed a fine of $2 billion on the company which essentially means that 40 percent of the company’s value may be wiped out. While the stock market may have imposed a trading price range of $90 and $110 on the company’s share price, it should efficiently change the permissible trading price limit to accommodate for the possible changes in the share price, else shareholders may struggle to trade at a fair price.

Regarding your private keys, can either keep them on a software wallet, or on a hardware wallet. The software wallet is the easiest way for beginners, but it implies that you have a computer that is properly secured (strong password, antivirus etc.) and that you do backups of your data. Remember, if you lose your private keys, the money is gone forever. As you get into cryptocurrencies more seriously, you will inevitably look for a hardware wallet, which is a dedicated device resistant to hacking where you can store your private keys (or to say it in an easy way, your crypto assets/invested money). I have already written an article on a hardware wallet, the TREZOR (see here). The most common wallets are the TREZOR and the Ledger Nano S. The TREZOR has a new model being sold from January 2018 (Model T) which will support much more currencies than the current TREZOR. The Ledger Nano S has more integrations currently, but I would recommend to wait for the TREZOR T to judge properly. Those devices usually cost around 100 USD, so once you have more than 100 USD to protect it starts making sense to get one.
The stock exchanges also maintain all company news, announcements, and financial reporting, which can be usually accessed on their official websites. A stock exchange also supports various other corporate-level, transaction-related activities. For instance, profitable companies may reward investors by paying dividends which usually comes from a part of the company’s earnings. The exchange maintains all such information and may support its processing to a certain extent. (For related reading, see "How Does the Stock Market Work?")
Investing is a way to set aside money while you are busy with life and have that money work for you so that you can fully reap the rewards of your labor in the future. Investing is a means to a happier ending. Legendary investor Warren Buffett defines investing as "… the process of laying out money now to receive more money in the future." The goal of investing is to put your money to work in one or more types of investment vehicles in the hopes of growing your money over time.
The recent market turbulence from the coronavirus pandemic has reinforced the importance of this approach. The stock market has recently gone through each of the three possible stages: market in confirmed uptrend, uptrend under pressure and market in correction. To stay protected throughout these changes, follow the No. 1 rule of investing: Always cut your losses short. While you can't control what the stock market does, this basic rule lets you control how you react.
Once you are familiar with the concepts above, and know that you can (and eventually will) be influenced, you need to do some research on what projects you want to invest into. There are to date 1400+ cryptocurrency projects listed on coinmarketcap, a website that tracks projects, market value etc. This is a good start to understand market capitalisation, price of the cryptocurrency unit in what we understand when we begin (fiat currency i.e. dollars or anything else), total amount of assets in circulation etc.
For example, there may be three buyers who have placed orders for buying Microsoft shares at $100, $105 and $110, and there may be four sellers who are willing to sell Microsoft shares at $110, $112, $115 and $120. The exchange (through their computer operated automated trading systems) needs to ensure that the best buy and best sell are matched, which in this case is at $110 for the given quantity of trade.
What would make me sell: Sometimes there are good reasons to split up. For this part of your journal, compose an investing prenup that spells out what would drive you to sell the stock. We’re not talking about stock price movement, especially not short term, but fundamental changes to the business that affect its ability to grow over the long term. Some examples: The company loses a major customer, the CEO’s successor starts taking the business in a different direction, a major viable competitor emerges, or your investing thesis doesn’t pan out after a reasonable period of time.