Spread it over the garden and wet it down to hold it in place.
You can mulch with lots of different materials, but I recommend starting by spreading newspaper across the entire garden, about 10 sheets thick. Get it from your neighbor if you have to. Or go to the local convenience store and ask them for a pile of old papers that didn’t sell. Spread it over the garden and wet it down to hold it in place. If you can’t get newspaper, then use a single layer of paper grocery bags. Cut them open and spread the paper out over the garden. Then, cover the newspaper or paper grocery bags with a layer of mulch. I use last autumn’s leaves on top of the newspaper, but you could also use a bale of straw (not hay, which has too many weed seeds) from a feed store or grass clippings you collect from your lawn (as long as it hasn’t been treated with any pesticides or herbicides this season!). This “good stuff” on top of the newspaper or paper bags should be about 2 inches thick.