AltCoins are those cryptocurrencies that came in existence after bitcoin has layed a successful foundation in the decentralized and financial ecosystem known to be cryptocurrency.
To invest, you either have to go through regulatory financial institutions that fascinates bitcoin or crypto transitions. That's if your region support the privileges since most governments are biased to the decentralized blockchain.
In this case of your beginning I think it's going to be difficult for you to buy bitcoin from an unknown supply unless you have someone trusted to do the deal others, you can as well buy from vendors in the Centrslized exchange platforms.

Note that iinvestment on bitcoin you hears about isn't a quick rich investment. To be successful in this volatile market, you need to be patient for quite a long time.
Als note, investing in the AltCoins is not same as investing in bitcoin. A lot of beginners get their funds lost on AltCoins while intended to invest on bitcoin.
Another important note is that you should verify every bitcoin or crypto informations across the media before you acts. This will help you not to be mislead or fall to scam.