I know Taproot is a soft fork, which basically means an upgrade. I see some forks have coins and some don't, I am lost on the difference and why. Litecoin is a fork and many others are that have coins as well. I don't know where to buy the new coins if there are any as well.
Taproot is an upgrade to Bitcoin. It is not a separate coin.
The term fork can mean many different things, depending on the context. Generally there are 2 types of forks - code forks, and blockchain forks. Of blockchain forks, there are additionally 2 more types - hard fork and soft fork.
A code fork is when someone copies the source code and then makes modifications on it so that it becomes something distinctly different. Many altcoins, such as Litecoin, are code forks of Bitcoin in this way. They were created when someone copied the Bitcoin source code, changed parameters and made several other modifications, and created their own coin. Because altcoins were created to be distinct alternatives to Bitcoin, they also have their own blockchains distinct from Bitcoin by having different genesis blocks. Such forks pertain to open source software in general.
A hard fork is when the consensus rules for the blockchain are changed in a way that is incompatible with the previous rules. Such a change could result in two (or more) diverging chains. These chains would share common ancestry. Nodes that are not upgraded would follow the chain which conforms to the old rules. Those non-upgraded nodes would consider the other chain in the fork to be invalid.
A soft fork is when the consensus rules for the blockchain are changed in a way that is compatible with the previous rules. Such a change could result in two (or more) diverging chains. However non-upgraded nodes would still consider blocks in the new rules chain to be valid and could switch to using that chain if it were the heavier chain.
It is possible to have both a code fork and a blockchain fork at the same time. For example, Bitcoin Cash is a hard fork from Bitcoin. It uses the same genesis block as Bitcoin does and shares several hundred thousand blocks with Bitcoin. However, some code forks of Bitcoin Core were created which introduced a new rules which was incompatible with Bitcoin's rules, and so a hard fork occurred and Bitcoin Cash was created. One of the primary node software for Bitcoin Cash is called Bitcoin ABC. This software is a code fork of Bitcoin Core.
Taproot is only a soft fork. It's consensus rules are implemented in the main Bitcoin node software. It is designed in such a way that non-upgraded nodes will still regard blocks containing transactions that spend Taproot outputs as being valid. So Taproot is a soft fork and there will not be a new coin for it.