ICO's are usually not available on exchanges while they are in an ICO phase. That is basically what ICO means: before it's available on the markets.
Usually there will be a website where you can sign up for the ICO, and where you can send payment (usually in Ethereum but not always) and then receive your ICO tokens. You won't be able to do much with these tokens yet, as like I said, they won't be supported on exchanges yet although they may be soon after their initial offering. Hope this helps.

I'd steer clear of ICO's as a newbie though. It's double speculative in an already speculative market. If you want a higher risk/reward ratio, try looking beyond the top 20 coins. A smaller market cap means a coin has a lot more room to grow. If I were to make suggestions of coins with small market caps and good potential I would recommend LBRY credits and Basic Attention Tokens. I still would not put most of my investment in those, because they are higher risk and not every project has an equal potential future market cap. For example, even though I expect something like Siacoin to significantly grow, I don't expect it to ever reach the same levels of Ethereum, simply because I think Ethereum is a stronger project than Siacoin. Good luck!