For each database you search, include this information:
You can document your detailed search strategy in several ways: screenshots, print as pdf, copy & paste, or (in certain databases) by downloading your search history. All these options work; just make sure you include the terms and number of results for each line of your search.
In most databases you can set up an account and save your search history; this is useful while you are creating your search and for documentation afterwards -- especially if you somehow lose track of your screenshots!
You can handle time period coverage in two ways. If you search using a date limit, that's the time period of your search! If you search without a date limit, check the database documentation to find out the date coverage of that database.