The leg has a pivot thing at the bottom that should slide into the bracket on the van.
At the top of the bracket is a pin that slides up. Push it up, then insert the top part of the leg pivot in under the pin. Then push the pivot flush with the van and let it drop into the bracket. Presto.
We have found that it is much handier to just keep the legs straight down on the ground, rather than using the bracket. The pivot part has holes so you can hammer a tent peg through the hole into the ground.
1990 Dodge Leisure Van - great camping
2006 Goldwing - terrific two-up riding
2011 Malibu LT - wonderful winter wheels