You can add a pic frame and write on piece of paper any names u do know and also write benevolent ancestors k own and unknown on it. Something with all elements...candle, crystals etc , white table cloth and when u cook, place a small offering of what you prepared. As u go things will come to you. It can be a small alter
Talk to them, make an altar for them.
Look on YouTube or google. There a plenty of ways you learn without knowing who they are. Do your research
Set up an altar if you have space, talk to them, commune with them, offer foods and drinks that you know they liked. Burn ancestor money.