Well, first you need a timing light. You may want to get a higher end one if you think you'll own old cars. https://www.amazon.com/gp/product/B000EVU8J8
Next you want to locate and clean your timing marks on the engine block.
After that, rotate your engine to TDC and find the mark on the engine pulley. You will probably want to mark it with a dab of white paint. White nail polish is great for this.
Get a baseline timing. If it's not at 15 degrees, turn off the car and loosen the bolt on the distributor. It's on the bottom side of the mounting point. (See photo) Start the engine again.
To increase timing (more degrees), rotate counter clockwise (A - advance). To decrease timing, rotate clockwise (R - retard). Keep measuring your timing, shooting for about 15 degrees.
If you cannot rotate the distributor enough with that adjustment, you may need to loosen the other bolt. First, rotate the distributor so it's in the middle of the indicator.
Then loosen the other bolt on the distributor.
Rotate the distributor just like you did before with the engine running and checking timing. If you can't get it close to 15 degrees with both bolts loose, something isn't right.
After you get the timing set, make sure you secure both bolts so your timing doesn't change.