There’s the notion of share capital and a separate notion of authorised share capital (which, confusingly, isn’t necessarily share capital).
Share capital consists of all funds raised by a company in exchange for shares of either common or preferred shares of stock.
Authorized share capital is the number of stock units (shares) that a company can issue as stated in its memorandum of association or its articles of incorporation. Authorized share capital is often not fully used by management in order to leave room for future issuance of additional stock in case the company needs to raise capital quickly.
If your 100,000 shares were simply authorised but not issued, it means you can issue up to that many shares. How many shares you actually issue is a separate matter.
If you issued all the 100,000 shares to yourself at $1 per share, you personally would have bought that many shares. The $100,000 could be funded by cash. If you didn’t pay for the shares, you’d owe the company $100,000.
Capital gains are only calculated when you sell, and is the difference between what you paid on purchase and what you got back on the sale. The price could go up and down, but unless you are obliged to (or perhaps elect to) revalue the asset to the prevailing market price, you have not made any capital gain or loss until you actually sell.
Disclaimer: I am not a tax, finance or law professional and the above is not professional advice of any kind. Please seek professional advice where appropriate.