Find your extender leaf. If it has been a while since you used your outdoor table -- if the winter months are long, for example -- you may have to get it out of storage. If it was stored in a damp area such as a basement or garage, it may have swelled from dampness. If it has, you may wish to buy a new leaf or have the manufacturer replace it.
Open up the tabletop by grasping one end and pulling it. If your tabletop is stubborn, you may need a hand from an obliging friend or family member, so that both ends of the table can be tugged at once.
Fill the separation in the table by placing the leaf neatly into the gap.
Coax the halves of the table top inward toward the leaf until no space is visible between the parts.
Place your hands on either side of the fold-down leaf.
Pull up gently on the leaf until it is flush with the top of the table.
Listen for a sound that will indicate the leaf is secure in its extended position. The sound may be akin to a click or a snap. Some tables with leaves have a latch under the fold that needs to be secured.
Measure the dimensions of your outdoor table. If your outdoor table does not have extender leaves, you will have to employ other tables of a similar height and width to extend it. Take careful measurements of your existing outdoor table so that you will be able to match table height and width as closely as possible.
Get a table of the same height and width as your outdoor table. It is nice if the second table is made of the same material as your outdoor table, but it is not a necessity. If you do not already have a table that boasts the same dimensions as your outdoor table, you may need to shop for one at home, furniture or department stores or big-box retailers. You can also build a table to the dimensions you need.
Position the second table right up against your outdoor table.
Unfurl a tablecloth and lay it across the two tables, so that the gap between the tables will not be seen.
Let the users of the table know where the two tables meet. Both guests and food prep help should be warned against placing dishes, glasses -- or even diners' elbows -- atop the gap to forestall spills and injury.