Can rainbow tables find the preimage of a hash? Given a hash value, how are you supposed to find its preimage? What steps can I take to solve find the preimage of a hash such as this 2d202cb6a781edf6ac01d14e1dd6367497db90ba9e8ad721fd17239228a213f9 (SHA256)
The only way to find the preimage of a hash value is to guess. There is no better way than trying all possible inputs by brute force until you find a match. This property is a design goal for cryptographic hash functions (preimage resistance).

A rainbow table doesn't help finding preimages, as such. Rather, it's a tool that helps you reuse somebody else's brute force work. If a rainbow table contains 1 trillion entries, then you can use it to find the preimage of any of those 1 trillion hash values in a short time. But the maker of this table had to make the 1 trillion hash computations. The reason rainbow tables are (occasionally) useful is that once the table has been built (a high one-time cost), you can make as many queries as you want (very low cost per query). It is useful if you have reason to believe that the preimage is among the 1 trillion in the table — if the preimage isn't one of these then all the rainbow table will tell you is that it definitely isn't one of these. See Crunge's answer on Security Stack Exchange for a very nice explanation of how rainbow tables work.

In practice looking up a hash value on Google is a low-effort way to find some simple preimages. When that doesn't work, it tends to suggests that tying to invert the hash won't be the easiest method of solving your problem.

Looking for the hash value in your question turns up a partial copy of a homework assignment which mentions “You should use the tools provided in the file, but are not limited to them.” Said file was not included in that copy of the assignment, but it should be in yours. What you need to do to solve the assignment is, presumably, to figure out how the provided tools work.