On most exchanges, you need to find the market pairs LTO is traded for. Prominent examples include:
... and many more.
Once you found the right pair for you make sure you have enough funds to make your transaction.
Buying is mostly an automated process. Once you found the right LTO pair and have enough funds available on the exchange you simply place your order and wait until it is filled.
Afterward, you will see your LTO position in your exchange asset overview. This asset summary can be called Wallets, Assets, even Funds sometimes, and will list all your tokens available to you. Selecting LTO tokens usually opens up a detailed view of your LTO position and allows you to withdraw LTO tokens from the exchange to, for example, your LTO web wallet where you can participate in staking LTO tokens.
If the exchange offers transfers to the LTO mainnet the process is quite simple. Simply copy your LTO web wallet address and transfer your LTO tokens to this exact address. Most exchanges will take a little fee.
If the exchange is only offering exchange tokens (e.g., ERC-20 or BEP-2), you should use the LTO token bridge instead. The process is quite similar to the 'exchange token to mainnet' tutorial:
The only difference is that you transfer the exchange funds to the token bridge address provided. That's it, after the transaction from the exchange goes through you will be credited your tokens to your LTO web wallet by the bridge.