Ah, welcome. The easiest way is click the "edit" button and then select "ID" that editor is quite userfriendly. If you want to do more advanced edits the "JOSM" editor is better, but it has a steeper learning curve and requires installing some software.

All edits are directly saved to the database but it can take a few hours for them to be rendered. Usually, after an hour zoom in on the affected area and reload, then your eddits will show up.