Your question is IMHO both somewhat out of scope for this forum and so general that it would require a lot of explanatory answering.
My best advice would be to get the book
"The Mushroom Cultivator" by Paul Stamets. Read the book and start practicing.
Alternatively, if you don't want to do some study and invest in tooling: buy a bag of pre-sterilized rye grains and a spore syringe containing spores of a truffle strain. You can find both for sale online and the spores are legal in most jurisdictions. When they arrive, inoculate bag with syringe, incubate bag, harvest.